M

E
En
gl
ish
Ce
nt
er
ME English Center. Physics guess paper ( 2025 )

Chapter 15 ( Molecular Theory of

Gasses )
Most important MCQs of chapter 15

1) For a monatomic ideal gas, the ratio of average kinetic energy per molecule to
average potential energy per molecule is:

a)​ 1:1

er
b)​ 2:1
c)​ All energy is kinetic, so ratio is ∞

nt
d)​ 3:2

a)​ 1.2
b)​ 1.33
Ce
2. For a monoatomic ideal gas, the ratio r=Cp/Cv is:
ish
c)​ 1.67
d)​ 2.0
gl

3. What happens to the average kinetic energy of gas molecules when the temperature
En

is increased at constant volume?

a)​ The average kinetic energy decreases.
b)​ The average kinetic energy remains constant.
E

c)​ The average kinetic energy increases.

d)​ The average kinetic energy becomes zero.
M

4. Which gas law is derived from the assumptions of the kinetic molecular theory?
a)​ Boyle's Law
b)​ Charles's Law
c)​ Avogadro's Law
d)​ Ideal Gas Law

5. Which of the following gases would have the highest average molecular speed at the
same temperature?

a)​ Helium (He)

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b)​ Neon (Ne)

c)​ Argon (Ar)
d)​ Krypton (Kr)

6) If the absolute temperature of a gas is increased 3 times, the rms velocity of the
molecules will
be
a)​ 3 times
b)​ 9 times
c)​ √3 times
d)​ 1/3 times

er
7) A gas is enclosed in an isolated container which is placed on a fast-moving train
uniformly.

nt
The temperature of the gas:
a)​ Increases due to the motion of the train

c)​ Remains constant, Ce

b)​ Decreases due to the motion of the train

d)​ Fluctuates, depending on the train's speed and direction

ish

8) The normal human body temperature is:

gl

a)​ 98.6°F (37°C)

b)​ 99.6°F (37.4°C)
En

c)​ 100.4°F (38°C)

d)​ 101°F (38.3°C)
E

9) The relationship between temperature and average kinetic energy of particles in a

gas is
M

a)​ temperature is inversely proportional to average kinetic energy

b)​ temperature is directly proportional to average kinetic energy
c)​ temperature is independent of average kinetic energy
d)​ temperature is proportional to the square of average kinetic energy

10) The Avogadro's number is the number of molecules in:

a)​ One mole of a substance
b)​ One kg of a substance
c)​ One 𝑚3 of a gas
d)​ One kilogram of hydrogen gas

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1)​ c 2)​ c 3)​ c 4)​ d 5)​ a

6)​ c 7)​ c 8)​ d 9)​ b 10)​ a

Most important Short Questions of chapter 15

1.​ Derive general gas law by making use of gas loss ?

2.​ Define and explain Charles law ?
3.​ Explain centigrade or Celsius scale and kelvin scale?
4.​ Briefly explain the triple point of water ?

Most important Numerical of chapter 15

er
nt
1)​ An air storage tank whose volume is 112 liters contains 3 kg of air at a pressure
of 18 atmospheres. How much air would have to be forced into the tank to

Ce
increase the pressure to 21 atmospheres, assuming no change in temperature?
Ans( ∆𝒎 = 𝒎𝟐 − 𝒎𝟏 = 𝟎. 𝟓 𝒌𝒈 ).
ish
2)​ The boiling point of liquid nitrogen is -321°F. Change it into equivalent Kelvin
temperature. Ans( 𝑻𝑲𝑵𝟐 = 𝟕𝟔. 𝟖𝟖𝟖 𝑲 ≈ 𝟕𝟕 𝑲 )
gl

3)​ 15.7. A sample of a gas contains 𝟑. 𝟎 × 𝟏𝟎𝟐𝟒 atoms. Calculate the volume of the
En

gas at a temperature of 300 K and a pressure of 120K Pa. Ans( 𝑽 = 𝟎. 𝟏𝟎𝟒 𝒎3 )

Most important Long Question of chapter 15

E

1)​ Describe the molecular movement causes the pressure exerted by gas, derive
M

pressure P= ⅓ pV2 .
2)​ Define and explain Boyle's law, Charles's and Avogadro's law.

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Chapter 16 ( First Law of

Thermodynamics )
Most important MCQs of chapter 16

1) A system absorbs heat and does work. What is the change in internal energy?
a)​ 100 J
b)​ 200 J
c)​ 300 J

er
d)​ 700 J

nt
2. Which of the following is the correct expression for the first law of thermodynamics?
a)​ ∆U=Q+W
b)​ ∆U=Q-W
c)​ ∆U=W-Q
d)​ ∆U=-(Q+W)
Ce
ish

3. In an isothermal process, the change in internal energy is:

gl

a)​ Positive
b)​ Negative
En

c)​ Zero
d)​ Depends on pressure
E

4. If a gas undergoes an isothermal expansion, how is the first law of thermodynamics

expressed?
M

a)​ Q=W
b)​ ∆U=Q
c)​ ∆U=0
d)​ Q=0

5. For an adiabatic process, which of the following is true according to the first law of
thermodynamics?
a)​ ∆U=Q
b)​ Q=0
c)​ W=0
d)​ ∆U=0

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6) What is internal energy in a thermodynamic system?

a)​ The energy associated with motion
b)​ The energy associated with the system's position
c)​ The sum of kinetic and potential energy
d)​ The total energy contained within the system

7) What is the characteristic of an adiabatic process?

a)​ Constant pressure
b)​ No heat exchange with the surroundings
c)​ Constant temperature
d)​ Constant volume

er
8) In an isochoric process, what is the primary feature?

nt
a)​ Constant temperature
b)​ No work done
c)​ Constant volume
d)​ No heat exchange Ce
ish
9) During an adiabatic process, what happens to the internal energy of the system?
a)​ Increases
gl

b)​ Decreases
c)​ Remains constant
En

d)​ Depends on the specific heat

10) In which thermodynamic process does a system exchange heat with its
E

surroundings but undergoes no change in temperature?

a)​ Isothermal process
M

b)​ Adiabatic process

c)​ Isobaric process
d)​ Isochoric process

1)​ c 2)​ b 3)​ c 4)​ c 5)​ b

6)​ c 7)​ b 8)​ c 9)​ d 10)​ a

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Most important Short Questions of chapter 16

1.​ What is work done by a gas drive W= P∆V?

2.​ Explain the first law of thermodynamics ?
3.​ Explain heat capacity, specific heat capacity and molar specific heat capacity ?
4.​ The relation between Cp and Cv for an ideal gas?

Most important Numerical of chapter 16

1)​ A 50 g piece of copper at 100°C is placed in 200 g of water at 20°C. If the final
temperature of the system is 30°C, calculate the specific heat capacity of copper.
(Specific heat capacity of water=4.18 J/g°C). Ans ( C𝒄 = 𝟐. 𝟑𝟒 𝑱/𝒈℃ ).

er
2)​ A gas expands from 0.03 m3 to 0.06 m3 against a constant pressure of 100 kPa.

nt
Calculate the work done in both a reversible and an irreversible process, and
compare the results. Ans ( ∆𝑾𝒓𝒆𝒗𝒆𝒓𝒔𝒊𝒃𝒍𝒆 = 𝟑𝟎𝟎𝟎 𝑱 )

Ce
3)​ A system undergoes an isobaric process where the pressure is kept constant at
150 kPa. If the volume increases from 0.05 m3 to 0.08 m³, calculate the heat
ish
added to the system. While change in internal energy during the process is -3900
Ans ( ∆𝑸 = 𝟔𝟎𝟎 𝑱 )
gl

Most important Long Questions of chapter 16

En

1.​ Briefly explain isochoric, isobaric, isothermal and adiabatic processes?

E
M

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Chapter 17 ( Second Law of

Thermodynamics )
Most important MCQs of chapter 17

1) Which of the following statements represents the Kelvin–Planck statement of the

Second Law?
a)​ Heat cannot of itself flow from colder to hotter body.
b)​ It is impossible to construct a cyclic engine that converts all the heat absorbed

er
into work.
c)​ No heat engine can have efficiency equal to 1.

nt
d)​ Both B and C.

Ce
2. The Clausius statement of the second law of thermodynamics is:
a)​ Work can be completely converted into heat.
b)​ Heat cannot spontaneously flow from a colder body to a hotter body.
ish
c)​ The efficiency of the Carnot engine is maximum.
d)​ Heat energy is conserved.
gl

3. Which of the following represents an irreversible process as described by the second

En

law of thermodynamics?
a)​ Ideal gas expansion without friction
b)​ Freezing of water at 0°C
E

c)​ Heat transfer from a hot object to a cold object

d)​ Melting of ice at 0°C
M

4. The second law of thermodynamics implies that:

a)​ Perpetual motion machines of the second kind are possible.
b)​ No engine can be more efficient than a Carnot engine operating between the
same two temperatures.
c)​ The total entropy of the universe remains constant
d)​ All processes are reversible in nature.

5. According to the second law of thermodynamics, what happens to the entropy of an

isolated system?
a)​ It remains constant.

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b)​ It decreases.
c)​ It increases or remains constant.
d)​ It fluctuates.

6 A refrigerator, with its door open. The temperature of the room will
a)​ Rise
b)​ Fall
c)​ Remains the same
d)​ Rise or fall depending on the area of the room

7. Which device is not used in a diesel engine

a)​ Outlet Valve

er
b)​ Piston
c)​ Sparking Plug

nt
d)​ Injector

a)​ Slow compression of an elastic spring Ce

8. Which one of the following processes is irreversible?

b)​ Slow evaporation of a substance in an isolated vessel

ish
c)​ Slow compression of a gas
d)​ A chemical explosion
gl

9. According to 2nd law of thermodynamics, 100% conversion of heat into mechanical

En

work is
a)​ Possible
b)​ Possible, if the conditions are ideal
E

c)​ Not possible

d)​ Possible, if the process is adiabatic
M

10) The efficiency of diesel engine is

a)​ Greater than petrol engine
b)​ Less than petrol engine
c)​ Equal to petrol engine
d)​ both have efficiency 1

1)​ b 2)​ b 3)​ c 4)​ b 5)​ c

6)​ a 7)​ c 8)​ d 9)​ c 10)​ a

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Most important Short questions of chapter 17

1.​ Explain the working principle of heat engine and also derive the formula for its
efficiency ?
2.​ Explain the second law of thermodynamics ?
3.​ Explain entropy ?
4.​ Briefly explain the refrigerator and the efficiency of a refrigerator ?
5.​ What is a Carnot engine?

Most important Numerical of chapter 17

er
1.​ A heat engine performs work of 0.4166 watts in one hour and rejects 4500 J of

nt
heat to the sink. What is the efficiency of the engine? Ans ( 𝜂 = 0.249 → 𝜼 = 𝟎.
𝟐𝟒𝟗 × 𝟏𝟎𝟎% = 𝟐𝟒. 𝟗% ).

Ce
2.​ Temperature difference between the surface water and bottom water in
Manchester Lake might be 5°C. Assuming the surface water to be at 20°C. What
ish
highest efficiency a steam engine could have if it operates between these two
temperatures? Ans ( 𝜼 = 𝟏. 𝟕𝟏 % )
gl

3.​ A heat engine works at the rate of 500 kW. The efficiency of the engine is 30%.
En

Calculate the loss of heat per hour. Ans ( 𝑸2 = 𝟏. 𝟏𝟕 × 𝟏𝟎𝟔 × 𝟑𝟔𝟎𝟎 = 𝟒. 𝟐 × 𝟏𝟎𝑱
E

Most important Long of chapter 17

M

1)​ Give the two statements of the second law of thermodynamics. Elaborate the
concept of entropy and state the second law of thermodynamics in terms of this
concept.
2)​ Describe the concept of reversible and irreversible process.

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Chapter 18 ( Magnetic Field )

Most important MCQs of chapter 18

1) The magnetic field around a current-carrying straight conductor is in the form of:
a)​ Straight lines
b)​ Concentric circles
c)​ Parallel lines
d)​ Ellipses

2. The direction of the magnetic field around a current-carrying conductor can be

er
determined by:
a)​ Fleming's left-hand rule

nt
b)​ Ampere's circuital law
c)​ Right-hand thumb rule
d)​ Lenz's law Ce
ish
3. Which of the following statements is correct about the magnetic field inside a
solenoid?
a)​ The magnetic field is uniform inside the solenoid.
gl

b)​ The magnetic field is zero inside the solenoid.

c)​ The magnetic field is stronger at the ends of the solenoid.
En

d)​ The magnetic field is directed opposite to the current.

4. A charged particle moves in a magnetic field. The force on the particle will be
E

maximum when the angle between the velocity of the particle and the magnetic field is:
M

a)​ 0°
b)​ 45°
c)​ 90°
d)​ 180°

5. Which of the following is true about the magnetic field at the center of a circular
current loop?
a)​ The magnetic field is zero at the center.
b)​ The magnetic field is directed along the plane of the loop.
c)​ The magnetic field is perpendicular to the plane of the loop.
d)​ The magnetic field decreases as the radius of the loop increases.

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6) Strength of magnetic field of solenoid can be increased by:

a)​ Increasing number of turns
b)​ increasing the current through the solenoid
c)​ inserting a ferromagnetic core (e.g. iron) into the solenoid
d)​ All of the above

7. The magnetic field inside along solenoid is:

a)​ equal to zero
b)​ uniform
c)​ decreases as we go away from the center to surface
d)​ increases as we go to wards the surface

er
8 The force between two current carrying conductor arises due to
a)​ Magnetic effect of current

nt
b)​ Polarization
c)​ Electromagnetic induction
d)​ Electrostatic interaction
Ce
9. To measure a higher voltage, what should you do with the voltmeter's internal
ish
resistance?
a)​ Increase it
gl

b)​ Decrease it
c)​ Keep it the same
En

d)​ It doesn't affect the measurement.

10. A proton moves perpendicular to a uniform magnetic field. What is the direction of
E

the force
experienced by the proton?
M

a)​ Parallel to the magnetic field

b)​ In the direction of the proton's velocity
c)​ Perpendicular to the magnetic field and the proton's velocity
d)​ Opposite to the direction of the proton's velocity

1)​ b 2)​ c 3)​ a 4)​ c 5)​ c

6)​ d 7)​ b 8)​ a 9)​ a 10)​ c

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Most important Short questions of chapter 18

1.​ What is a galvanometer, and what is its primary function in an electrical circuit?
2.​ Define magnetic field?
3.​ Explain Magnetic force on a current carrying conductor and drive its formula
F = I (L×B)?
4.​ What is magnetic flux? explain maximum magnetic flux minimum magnetic flux?
5.​ Briefly explain ampere law and its application ?

Most important Numerical of chapter 18

1.​ A solenoid has length 𝑳 = 𝟏. 𝟐𝟑 𝒎 and inner diameter 𝒅 = 𝟑. 𝟓𝟓 𝒄𝒎, and it carries a

er
current 𝑰 = 𝟓. 𝟓𝟕 𝑨. It consists of five close-packed layers, each with 850 turns
along length 𝑳. What is 𝑩 at its center? Ans( B = 𝟐𝟒. 𝟐 𝒎𝑻 )

nt
Ce
2.​ Compute the magnitude of the magnetic field of a long, straight wire carrying a
current of 𝟏 𝑨 at distance of 𝟏 𝒎 from it. Compare it with Earth's magnetic field.
Ans( 𝑩 = 𝟐 × 𝟏𝟎-7 𝑻 )
ish
3.​ Suppose we have a toroid with 1000 times and current of 3 amperes flowing
through it. The toroid has a circular cross-section with a radius of 0.1 m calculate
gl

the magnetic flux density inside the toroid. Ans( B= 3.77 mT )

En

Most important Long questions of chapter 18

E

1)​ Describe the basic working principle of a voltmeter. How does it measure voltage
M

across a component in a circuit?

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Chapter 19 (Electromagnetic Induction)

Most important MCQs of chapter 19

1) The induced emf in a coil is directly proportional to:

a)​ Current in coil
b)​ Resistance of wire
c)​ Rate of change of magnetic flux
d)​ Length of coil

2. Lenz’s law is based on the principle of:

er
a)​ Conservation of energy
b)​ Conservation of mass

nt
c)​ Conservation of momentum
d)​ Ohm’s law
Ce
3. When a magnet is moved towards a coil, the induced current in the coil:
ish
a)​ Flows in the direction of the magnetic field
b)​ Flows in a direction to support the motion of the magnet
c)​ Flows in a direction to oppose the motion of the magnet
gl

d)​ Flows only if the coil has an iron core

En

4. Which of the following devices works on the principle of electromagnetic induction?

a)​ Battery
b)​ Transformer
E

c)​ Resistor
M

d)​ Capacitor

5. In a transformer, electromagnetic induction is used to:

a)​ Increase the current and voltage
b)​ Decrease the current and voltage
c)​ Increase or decrease the voltage
d)​ Convert AC to DC

6 The magnitude of induced e.m.f. increases with

a)​ the decrease in the speed of the conductor's motion.
b)​ the decrease in the strength of the magnetic field.

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c)​ the increase in the number of turns in the coil.

d)​ the reduction in the area of the coil.

7. Faraday's law of electromagnetic induction states

a)​ that current in a circuit always opposes the change in magnetic flux.
b)​ that the induced e.m.f. is directly proportional to the rate of change of magnetic
flux.
c)​ that a changing electric field produces a magnetic field
d)​ that magnetic fields can only be produced by electric currents.

8. Lenz's law predicts the direction of an induced current

a)​ to conserve electric charge

er
b)​ by stating that the induced current will oppose the change causing it
c)​ by following the direction of the applied magnetic field.

nt
d)​ based on the magnitude of the electric field.

9. Eddy currents produce:

Ce
a)​ static electricity in conductive materials.
b)​ alternating magnetic fields with no heating effects
ish
c)​ magnetic fields that oppose the inducing field and cause heating in conductors.
d)​ uniform electric fields that have no impact on power generation.
gl

10 Laminated iron cores are used in electric motors and transformers to

En

a)​ reduce the weight of the device

b)​ enhance the mechanical strength
c)​ minimize eddy current losses and reduce heating
E

d)​ increase the magnetic permeability of the core

M

1)​ c 2)​ a 3)​ c 4)​ b 5)​ c

6)​ c 7)​ b 8)​ b 9)​ c 10)​ c

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Most important Short questions of chapter 19

1.​ Explain induced electromotive force EMF?

2.​ Explain Faraday's law of electromagnetic induction?
3.​ Define self-induction and explain how it occurs in a coil?
4.​ State Lenz's law and discuss its significance in the context of electromagnetic
induction?
5.​ Explain mutual induction?

Most important Numerical of chapter 19

1.​ An AC generator produces an alternating current with a maximum voltage of 240

er
V. If the frequency of the generated AC is 50 Hz, calculate the peak value of the

nt
voltage. Ans ( 𝑽𝒑𝒆𝒂𝒌 = 𝟑𝟑𝟗. 𝟒𝟏𝟏 𝑽 ≈ 𝟑𝟑𝟗 𝑽 )

Ce
2.​ Two coils are placed adjacent to each other, and a change in current in the first
coil induces an emf of 0.5 V in the second coil. If the mutual inductance is 0.2 H,
calculate the rate of change of current in the first coil. Ans( ∆𝑰 \ ∆t= 𝟐. 𝟓 𝑨/𝒔 )
ish
3.​ Two coils are placed close to each other. If a change in current of 3 A/s in the first
coil induces an EMF of 4 V in the second coil, calculate the mutual inductance.
gl

Ans( 𝑴 = 𝟏. 𝟑𝟑 𝑯 )
En

Most important Long questions of chapter 19

E

1.​ What are the common applications of DC motors in everyday devices?

M

2.​ Give detailed explanation of DC motor and also explain its working?

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Chapter 20 ( Alternating Current )

Most important MCQs of chapter 20

1. The standard frequency of AC supply in Pakistan is:

a)​ 50 Hz
b)​ 60 Hz
c)​ 100 Hz
d)​ 120 Hz

er
2. The frequency of standard household alternating current in Pakistan is:
a)​ 50 Hz (b) 60 Hz. (c) 100 Hz (d) 120 Hz

nt
3. The parameter for measuring the rate of change of alternating current or voltage with
respect to time is:
a)​ Amplitude
b)​ Frequency
Ce
ish
c)​ Phase angle
d)​ Peak Voltage
gl

4. In AC circuits, what is the phase difference between current and voltage in a purely
En

resistive circuit?
a)​ 0𝑜. (b) 45𝑜. (c) 90𝑜. (d) 180𝑜
E

5. A device used to measure the root mean square (RMS) value of an AC voltage or
current is:
M

a)​ Voltmeter
b)​ Oscilloscope
c)​ Ammeter
d)​ AVO meter

6. In an AC circuit, the term "reactance" represents the:

a)​ Ohmic resistance only
b)​ Resistance to DC currents only
c)​ Capacitive and inductive opposition to current flow
d)​ Total impedance, including resistance and phase angle
7. A type of a circuit characterized by equal values of resistance and reactance is:

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a)​ Resistive. (b) Inductive (c) Capacitive (d) Resonant

8. In an AC sine wave, the peak to peak voltage is:

a)​ Double the peak voltage
b)​ The difference between the peak voltage and zero
c)​ The sum of the peak voltage and zero
d)​ The difference between the positive and negative peak voltages

What is the power factor of a purely resistive circuit?

a)​ 0 (b) 0.5 (c) 1 (d) -1

10. The purpose of a transformers in an AC power distribution system.

er
a)​ To convert AC to DC
b)​ To step up or step down voltage

nt
c)​ To store electrical energy
d)​ To regulate current flow

1)​ a 2)​ a 3)​ b

Ce 4)​ a 5)​ d
ish
6)​ c 7)​ d 8)​ a 9)​ c 10)​ b
gl

Most important Short questions of chapter 20

En

1.​ What is alternative current ( AC)

2.​ Define RMS voltage and explain its significance in AC circuit?
3.​ Explain the difference between peak voltage, RMS voltage and average voltage
E

in an AC circuit?
M

4.​ Explain AC through an inductor?

5.​ What is an RLC circuit?

Most important Numerical of chapter 20

1.​ In a parallel RC circuit, the resistance (R) is 60 ohms, and the capacitance (C) is
30 µF. Calculate the total current flowing through the circuit at a frequency of 120
Hz? While voltage is 60 V. Ans ( 𝑰𝑻 = 𝟏. 𝟔𝟗 𝑨)

2.​ A resistor (R) of 20 ohms is connected in series with a capacitor (C) of 10 µF in

an AC circuit with a frequency of 50 Hz. Calculate the total impedance?

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Ans ( 𝒁 = 𝟑𝟏𝟖. 𝟗𝟒 𝒐𝒉𝒎𝒔 )

3.​ For an RLC circuit in parallel with a 5 ohm register, a 0.02 H inductor, and 0.005
F capacitor calculate the resonant frequency ff ? Ans ( ff =15.92 Hz).

Most important long questions of chapter 20

1.​ Give detailed explanation of resonance of parallel RLC AC circuit also drivers
formula?
2.​ Explain AC through inductor and drive V=Vosin(wt+π\2)

er
nt
Ce
ish
gl
En
E
M

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Chapter 21 ( Physics of Solid )

Most important MCQs of chapter 21
1. The property of a body by virtue of which it tends to regain its original size and shape
when the applied force is removed is called
a)​ Elasticity (b) Plasticity (c) Rigidity (d) Compressibility

2. Substances which can be stretched to cause large strains are called

a)​ Brittle (b) Ductile (c) Plastic (d) Elastomer

er
3. If the load is increased beyond the point, the strain increases rapidly for even a small
change in the stress

nt
a)​ Elastic point (b) Yield point (c) Plastic point (d) Fracture point

4. The reciprocal of the bulk modulus is called

(a) Compressibility (b) Volume stress Ce
(c) Modulus of rigidity. (d) Volume strain
ish
5. Which of the following statements is/are wrong?
i. Hollow shaft is much stronger than a solid of the same length and same mass
gl

ii. Reciprocal of bulk modulus of elasticity is called compressibility

iii. It is difficult to twist a long rod as compared to small rod
En

(a) III only (b) I only (c) II and III (d) I and II
E

6. Metals are good conductors of heat and electricity. This property is conferred by
a)​ Covalent b) lonic c) Metallic d) Hydrogen
M

7. For a metallic crystal, delocalized electrons occupied band is:

a)​ Conduction band (b) Valence band
c) Conduction and valence bands d) there are no delocalized electrons

8. The semiconductors have resistivity

a)​ Between conductor and insulator
b)​ More than insulators
c)​ Less than conductors.
d)​ Depending upon the semiconductor material property

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9 A ferromagnetic substance becomes a permanent magnet when it is placed in a

magnetic field
because
a)​ All the domains get oriented in the direction of the magnetic field.
b)​ All the domains get oriented in the direction opposite to the direction of the
magnetic field.
c)​ Domains get oriented randomly.
d)​ Domains are not affected by the magnetic field.

10. Identify methods to demagnetize a ferromagnet.

a)​ By cooling, heating, or submerging in water
b)​ By heating, hammering, and spinning it in an external magnetic field

er
c)​ By hammering, heating, and rubbing with cloth
d)​ By cooling submerging in water, or rubbing with cloth

nt
1)​ a

6)​ c
2)​ d

7)​ a
3)​ b

8)​ a Ce 4)​ a

9)​ a
5)​ a

10)​ b
ish

Most important Short questions of chapter 21

gl

1.​ What is deformation and also explain deformation in one dimension?

En

2.​ Explain shear modulus and bulk modulus with formula?

3.​ Explain electrical properties of solid ?
4.​ Define an energy band in solid ?
E

5.​ What does semiconductor explain intensive and extrinsic semiconductor?

M

Most important Numerical of chapter 21

1.​ The elastic limit of copper is 𝟏. 𝟓 × 𝟏𝟎8 𝑵 / 𝒎2 It is to be stretched by a load of 10

kg.Find the diameter of the wire if the elastic limit is not to be exceeded.
Ans ( 𝒅 = 𝟗. 𝟏𝟐 × 𝟏0-4𝒎 = 𝟎. 𝟗𝟏𝟐 𝒎𝒎 )

2.​ What would be the greatest length of a steel wire which is fixed at one end, and
can it be hanged freely without breaking? The breaking stress of steel is 𝟕. 𝟖 ×
𝟏𝟎8 𝑵 / 𝒎2 and the density of steel is 𝟕𝟖𝟎𝟎 𝒌𝒈/𝒎3 Ans ( 𝑳 = 𝟏. 𝟎𝟐 × 𝟏𝟎4 𝒎 )

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3.​ Calculate the change in volume of a lead block of volume 𝟏. 𝟑 𝒎³ subjected to a

pressure of 𝟏𝟐 𝒂𝒕𝒎. Also, calculate the compressibility of lead. Given the bulk
modulus as 𝑩 = 𝟖𝟎 ×𝟏𝟎9 𝑵 / 𝒎2
Ans (∆𝑽 = 𝟐. 𝟎𝟏𝟓 × 𝟏𝟎-5 m3
𝒄𝒐𝒎𝒑𝒓𝒆𝒔𝒔𝒊𝒃𝒊𝒍𝒕𝒚 = 𝟏. 𝟐𝟓 × 𝟏𝟎-11 𝒎/𝑵 )

Most important long questions of chapter 21

1.​ Describe hysteresis loss ?
2.​ Describe superconductivity and its applications.

er
nt
Ce
ish
gl
En
E
M

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Chapter 22 ( Solid State Electronics )

Most important MCQs of chapter 22
1. Silicon and Germanium are examples of:
a)​ Conductors
b)​ Insulators
c)​ Semiconductors
d)​ Superconductors

2. In a p-n junction diode under forward bias, the width of the depletion region:

er
a)​ Increases
b)​ Decreases

nt
c)​ Remains unchanged
d)​ Disappears

Ce
3. Which material is most commonly used in the manufacturing of semiconductor
devices?
ish
a)​ Germanium
b)​ Silicon
gl

c)​ Gallium Arsenide

d)​ Carbon
En

4. What happens to the conductivity of a semiconductor as temperature increases?

a)​ Conductivity decreases
E

b)​ Conductivity remains constant

c)​ Conductivity increases
M

d)​ It first increases and then decreases

5. A transistor is typically used as:

a)​ A resistor
b)​ A capacitor
c)​ An amplifier or switch
d)​ A diode

6 For a full-wave rectifier, the output frequency

a)​ Equals one-half the input frequency
b)​ Equals the line frequency

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c)​ Equals two times the input

d)​ Is three times the line frequency

7. LED construction needs a semiconductor material is:

a)​ Silicon (b) Germanium (c) Gallium (d) Gallium arsenide

8. The frequency of a half-wave signal is

a)​ Twice the line frequency
b)​ Equal to the line frequency
c)​ One-half of the line frequency
d)​ One fourth the line frequency

er
9. The voltage gain of an emitter follower circuit is
a)​ High (b) Low (c) Very high (d) Moderate

nt
10. What is also called the conventional amplifier?
a)​ Common-collector circuit
b)​ Emitter follower circuit
c)​ Common base circuit
Ce
ish
d)​ Common emitter circuit
gl

1)​ c 2)​ b 3)​ b 4)​ c 5)​ c

En

6)​ c 7)​ d 8)​ b 9)​ b 10)​ d

E
M

Most important Short questions of chapter 22

1.​ Explain intrinsic and extrinsic semiconductors?

2.​ What does doping also explain p type semiconductor and n type semiconductor?
3.​ Define PN junction diodes also explain forward bias and reverse bias?
4.​ What rectification explains half wave rectification and full wave rectification?
5.​ Define transistors and their characteristics

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Most important Numerical of chapter 22

1.​ A semiconductor diode laser has a peak emission wavelength of 1.55 µm. Find
its band gap in eV. Ans ( 𝑬𝒈 = 𝟎. 𝟖 𝒆𝑽 )
2.​ Find the value of 𝜷 if (i) 𝜶 = 𝟎. 𝟗 (ii) 𝜶 = 𝟎. 𝟗𝟖 (iii) 𝜶 = 𝟎. 𝟗𝟗. Ans ( 𝛽 = 99 , 𝛽 = 49
and 𝛽 = 9 )

3.​ Calculate 𝑰𝑬 in a transistor for which 𝜷 = 𝟓𝟎 and 𝑰𝑩 = 𝟐𝟎𝝁𝑨. Ans ( 𝑰𝑬 = 𝟏. 𝟎𝟐 𝒎𝑨 )

4.​ A Ge diode has a voltage drop of 0.4 V when 12 mA flow through it. If the same
470 Ohm is used, what battery voltage is needed? Ans ( 𝑽𝒃𝒂𝒕𝒕𝒆𝒓𝒚 = 𝟔. 𝟎𝟒 𝑽)

er
Most important Long questions of chapter 22

nt
1.​ Describe the I-V characteristic curves of P-N junction.

Ce
2.​ Describe a P-N junction (diode), discuss its forward and reverse biasing.
ish
gl
En
E
M

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Chapter 23 ( Digital Electronics )

Most important MCQs of chapter 23
1 What is the binary equivalent of the decimal number 13?
a)​ 1101
b)​ 1011
c)​ 1110
d)​ 1001

2. Which logic gate gives a high output (1) only when both inputs are high (1)?

er
a)​ OR gate
b)​ AND gate

nt
c)​ XOR gate
d)​ NOT gate

3. In digital circuits, a flip-flop is used to:

a)​ Perform arithmetic operations
Ce
ish
b)​ Store a single bit of data
c)​ Generate high frequency signals
gl

d)​ Reduce noise

En

4. Which of the following is a universal gate?

a)​ XOR gate
b)​ AND gate
E

c)​ NOR gate

d)​ OR gate
M

5. A multiplexer is used to:

a)​ Perform division
b)​ Select one of many inputs
c)​ Convert analog signals to digital
d)​ Store multiple bits of data

6 The behavior of 2 input AND gate, when both switches are closed, Lamp is
a)​ OFF (b) ON (c) Blinking (d) Flickering

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7. In a 3-input OR gate, if all inputs are '0' so the output will be:
a)​ 1 (b) 0 (c) Undefined (d) Both A and B

8. If the input is '1', the output of a NOT gate will be:

a)​ 1 (b) 0 (c) Undefined (d) Both A and B

9. In a 2-input XOR gate, when both inputs are '1' than the output will be
a)​ 1 (b) 0 (c) Undefined (d) Both A and B

10) Which combination of logic gates is equivalent to an XOR gate?

a)​ AND + OR (b) NOT + NOR (c) OR + NAND (d) AND + NAND

er
1)​ a 2)​ b 3)​ b 4)​ c 5)​ b

nt
6)​ b 7)​ b 8)​ b 9)​ b 10)​ d

Ce
Most important Short questions of chapter 23
ish

1.​ Explain digital signal level?

gl

2.​ Explain XOR Gate and XNOR gate?

3.​ Difference between analogue signal and digital signal?
En

Most important Numericals of chapter 23

E

Notes there is no numerical in this chapter

M

Most important long questions of chapter 23

1.​ Explain logic gates and explain all types of logic gates?

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Chapter 24 ( Relativity )
Most important MCQs of chapter 24
1 The General Theory of Relativity was a new way of understanding of
a)​ The speed of light (b) gravity (c) mass (d) force

2. An object at rest has a mass of 1 kg. What is its mass when it is moving at a speed of
0.9c?
a)​ Infinite (b) 1.2 kg (c) 2.3 kg (d) 1 kg

er
3) The equivalence of principle in general relativity is:
a)​ The equivalence of inertial and gravitational mass

nt
b)​ The equivalence of electric and magnetic fields
c)​ The equivalence of space and time
d)​ The equivalence of matter and energy
Ce
4. Which of the following phenomena is NOT predicted by special relativity?
ish
a)​ Time dilation b) Length contraction
c) Gravitational waves d) Relativistic mass increase
gl

5. What does the equivalence principle state about acceleration and gravity?
En

a)​ They are completely different forces

b)​ They are indistinguishable for an observer
c)​ Gravity is stronger than acceleration
E

d)​ Acceleration cancels out gravity

M

6. Light passing near a massive object like a star will bend due to:
a)​ Gravitational lensing.
b)​ refraction
c)​ reflection
d)​ diffraction

7. What is the main reason astronomers cannot directly observe black holes?
a)​ They are too small
b)​ They deflect light
c)​ They are too far away
d)​ their immense gravity traps light

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8. Objects cannot exceed the speed of light because:

a)​ Their mass becomes infinite
b)​ Their length becomes zero
c)​ Time slows down to zero
d)​ they lose all energy

9. Why is the Galilean transformation not valid at high speeds?

a)​ It cannot handle accelerating frames
b)​ It violates the constancy of the speed of light
c)​ It only works in flat space time
d)​ It neglects time dilation effects

er
10 The example of inertial frame in our everyday life is:

nt
a)​ A car accelerating on a highway
b)​ A train moving smoothly at constant speed
c)​ A person standing on a spinning platform
d)​ an airplane encountering turbulence Ce
ish
1)​ b 2)​ c 3)​ a 4)​ c 5)​ b
gl

6)​ a 7)​ d 8)​ a 9)​ b 10)​ b

En

Most important Short questions of chapter 24

E

1.​ Explain frame of reference also explain types of frame of reference?

M

2.​ Explain the difference between Special and General Relativity in simple terms.
3.​ Calculate the value of 𝜸 (Lorentz factor) if the object is moving at the speed of
light.
4.​ Define special theory of relativity

Most important Numericals of chapter 24

1.​ At what speed will an object's relativistic mass be twice its rest mass? Ans (
v=√3c/2

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2.​ At what speed is a particle moving if the mass is equal to three times its rest
mass? Ans ( 𝒗 = 𝟐√2/𝟑)

3.​ At what velocity does the K.E of a particle equal its rest energy? Ans ( √3c/2)

Most important Long questions of chapter 24

1.​ How does the principle of relativity differ from the classical Galilean view?

er
nt
Ce
ish
gl
En
E
M

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Chapter 25 ( Quantum Physics )

Most important MCQs of chapter 25
1 The energy of a photon is directly proportional to:
a)​ Wavelength
b)​ Frequency
c)​ Amplitude
d)​ Speed

2. Which of the following phenomena demonstrates the wave-particle duality of light?

er
a)​ Reflection
b)​ Refraction

nt
c)​ Photoelectric effect
d)​ Diffusion

Ce
3. According to the Heisenberg Uncertainty Principle, it is impossible to simultaneously
determine the exact:
ish
a)​ Energy and position of a particle
b)​ Position and momentum of a particle
gl

c)​ Velocity and energy of a particle

d)​ Mass and charge of a particle
En

4. In quantum mechanics, the principle that two fermions cannot occupy the same
quantum state is known as:
E

a)​ Pauli Exclusion Principle

b)​ Hund's Rule
M

c)​ Bohr's Model

d)​ Aufbau Principle

5. Which of the following describes the probability distribution of a particle in quantum

mechanics?
a)​ Wave function
b)​ Classical trajectory
c)​ Orbit
d)​ Energy band

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6 The quantum number that specifies the shape of an orbital is:

a)​ Principal quantum number
b)​ Azimuthal quantum number
c)​ Magnetic quantum number
d)​ Spin quantum number

7. In the double-slit experiment, the interference pattern observed is evidence of:

a)​ Light behaving as a particle
b)​ Light behaving as a wave
c)​ The photoelectric effect
d)​ Particle collisions

er
8. In Photoelectric Effect, when light fall on the surface of metal, the material should
emit

nt
(a)​Electrons (b) Protons. (c) Positrons. (d) Neutrons

(a)​Maximum (b) Minimum

Ce
9. Threshold frequency is defined as the _________ frequency of incident light which
can cause photoelectric emission.
(c) Average (d) Highest
ish

10. The amount of energy which is necessary to start photoelectric emission is called.
gl

(a)​ Maximum (b) Average (c) Minimum (d) Littlest

En

1)​ a 2)​ c 3)​ b 4)​ a 5)​ a

6)​ b 7)​ b 8)​ a 9)​ b 10)​ c

E
M

Most important Short questions of chapter 25

1.​ Explain Plank's hypothesis ?

2.​ What is the threshold frequency?
3.​ Give construction of an electron microscope?
4.​ Explain blackbody radiation ?
5.​

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Most important Numericals of chapter 25

1)​ The temperature of your skin is approximately 32 °C. What is the wavelength at
which the peak occurs in the radiation emitted from your skin? Ans ( 𝝀 = 𝟗. 𝟓 ×
𝟏𝟎-6𝒎)

2)​ A light source of wavelength illuminates a metal and ejects photoelectrons with a
maximum kinetic energy of 1.0 eV. A second light source with half the
wavelength of the first ejects photoelectrons with a maximum kinetic energy of
4.0 eV. Determine the work function of the metal. Ans ( ∅ = 𝟐 𝒆𝑽 )

3)​ The work function for zinc is 4.24 eV which is the threshold frequency for the

er
ejection of photoelectron from zinc Ans ( v=1.02×1015Hz )

nt
Most important Long questions of chapter 26

Ce
1.​ Describe how energy is distributed over the wavelength range for different
temperatures.
ish
2.​ Give a detailed Explain Compton Effect?
gl
En
E
M

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Chapter 26 ( Atomic Physics )

Most important MCQs of chapter 26
1 The nucleus of an atom consists of:
a)​ Protons only
b)​ Neutrons only
c)​ Protons and neutrons
d)​ Protons and electrons

2. The atomic number of an element is determined by the number of:

er
a)​ Neutrons
b)​ Electrons

nt
c)​ Protons
d)​ Nucleons

Ce
3. Isotopes of an element have the same number of:
a)​ Protons but different numbers of neutrons
ish
b)​ Neutrons but different numbers of protons
c)​ Protons and neutrons
gl

d)​ Electrons but different numbers of protons

En

4. The emission of light from an atom occurs when an electron:

a)​ Moves to a higher energy level
b)​ Moves to a lower energy level
E

c)​ Remains in the same energy level

d)​ Collides with another electron
M

5. What force holds the protons and neutrons together in an atomic nucleus?
a)​ Gravitational force
b)​ Electromagnetic force
c)​ Strong nuclear force
d)​ Weak nuclear force

6).Laser action requires a medium with at least:

(a)​Three energy levels (b) Four energy levels
(c) Two energy levels (d) Five energy levels

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7. Population inversion occurs in:

(a)​ Active medium (b) Passive medium
(c) Gaseous medium (d) Vapour medium

8. X-rays transfer __________ to metals.

(a) Energy (b) Force (c) Pressure (d) Momentum

9. X-rays are deflected by:

(a) Magnetic fields
(b) Electric fields
(c) Gravitational fields
(d) No fields

er
10 Doubling the voltage of an X-ray tube:

nt
(a) Halves the intensity
(b) Keeps the intensity unchanged
(c) Doubles the intensity
(d) Quadruples the intensity Ce
ish
1)​ c 2)​ c 3)​ a 4)​ b 5)​ c
gl

6)​ a 7)​ a 8)​ a 9)​ d 10)​ b

En

Most important Short questions of chapter 26

E

1)​ Define Atomic Spectra ?

M

2)​ Explain spectral lines ? And write names of all series

3)​ Explain Bohr's model and its postulate?
4)​ Drive and explain Bohr's radius?
5)​ Explain that spectrum of hydrogen atoms ?

Most important Numericals of chapter 26

1.​ Calculate the speed of the electron if it orbits in (a) the smallest allowed orbit and
(b) the second smallest orbit? (c)If the electron moves to larger orbits, does its
speed increase, decrease, or stay the same?
Ans (𝒗𝟏 = 𝟐. 𝟏𝟗 × 𝟏𝟎2 𝒎/𝒔 and 𝒗𝟐 = 𝟏. 𝟎𝟗 × 𝟏𝟎6𝒎/𝒔 )

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2.​ What is the energy of the photon emitted by a hydrogen atom when the hydrogen
atom changes directly from the n = 5 state to the n = 2 state? Ans (∆𝑬 = 𝟐. 𝟖𝟓 𝒆𝑽)

3.​ What is the wavelength of light for the least energetic photon emitted in the
Balmer series of the hydrogen atom spectrum lines?
(b) What is the wavelength of the series limit? Ans ( 𝝀 = 𝟑𝟔𝟒. 𝟔𝟑 𝒏𝒎).

Most important long questions of chapter 26

1.​ What is Laser? Write the characteristics of Laser light. Can a two-level system be
used for the production of lasers? Why?
2.​ What are the postulates of Bohr's Model of hydrogen atom? Discuss the

er
importance of this model to explain various series of line spectra in hydrogen
atom

nt
Ce
ish
gl
En
E
M

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Chapter 27 ( Nuclear Physics )

Most important MCQs of chapter 27
1 Which of the following particles is emitted during beta decay?
a)​ Neutron b) Proton. c) Electron or positron d) Alpha particle

2. The process in which two light nuclei combine to form a heavier nucleus is called:
a)​ Fission b) Fusion c) Alpha decay d) Gamma emission

3. Which of the following is used as a fuel in nuclear reactors?

er
a) Carbon-12 b) Uranium-235 c) Hydrogen-2 d) Nitrogen-14

nt
4. In a nuclear fission reaction, the total mass of the products is:
a)​ Equal to the mass of the original nucleus

Ce
b)​ Less than the mass of the original nucleus
c)​ Greater than the mass of the original nucleus
d)​ Not related to the mass of the original nucleus
ish

5. Which of the following is a common moderator used in nuclear reactors?

gl

a) Uranium b) Heavy water c) Carbon dioxide d) Lead

En

6. Gamma radiation differs from alpha and beta radiation in that it:
a)​ Consists of charged particles
b)​ Is electromagnetic radiation
E

c)​ Has a shorter range in air

d)​ Is always accompanied by neutron emission
M

7 As the number of nucleons in a nucleus increases, the binding energy per nucleon:
a)​ Increases continuously with mass number
b)​ Decreases continuously with mass number
c)​ remains constant with mass number
d)​ First increases and then decreases with increase of mass number

8. Moderator in a nuclear reactor slows down the neutrons to:

a)​ Decrease the probability of escape
b)​ Increase the probability of nuclear fission
c)​ Decrease the probability of absorption

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d)​ all of the above

9. Emission of 𝛽+ particles by an element affects its atomic number Z in the following

way:
(a)​ Increases by 1 (b) decreases by 1 (c) Increases by 2 (d) remains the same

10. The half life period of a radioactive element is 100 days. After 400 days, 16 g of the
element will be reduced to
(a) 8g (b) 4g (c) 2g (d) 1 g
1)​ c 2)​ b 3)​ b 4)​ b 5)​ b

6)​ b 7)​ d 8)​ d 9)​ a 10)​ d

er
nt
Most important Short questions of chapter 27

1.​
2.​
Ce
Explain the law of radioactive decay with formulas ?
What is the exponential nature of radioactivity ?
ish
3.​ Define half life also explain nuclear fusion reaction and fusion reaction
4.​ Define nuclear reaction and explain conservation of atomic and mass numbers.
gl

Most important Numericals of chapter 27

En

1.​ Find the binding energy (in MeV) for lithium 73𝑳𝒊 (atomic mass = 7.016 003 u).
Ans ( 𝑬𝑩 = 𝟑𝟕. 𝟗 𝑴𝒆𝑽 )
E

2.​ In 9.0 days the number of radioactive nuclei decreases to one-eighth the number
M

present initially. What is the half-life (in days) of the material?

Ans ( 𝑻 𝟏/𝟐 = 𝟑 𝒅𝒂𝒚𝒔 ).

3.​ The binding energy of a nucleus is 225.0 MeV. What is the mass defect of the
nucleus in atomic mass units? Ans ( ∆m = 0.2415u)

Most important Long questions of chapter 27

1.​ What is radioactivity? State the law of radioactive disintegration. Show that
radioactive decay is exponential in nature.
2.​ Explain the main differences between alpha, beta, and gamma emissions.

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Chapter 28 ( Particle Physics )

Most important MCQs of chapter 28
1 What is the fundamental force responsible for holding quarks together within a
proton?
a)​ Gravitational force
b)​ Electromagnetic force
c)​ Strong nuclear force
d)​ Weak nuclear force

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2. Which of the following particles is considered a boson?
a)​ Proton b) Neutron c) Photon d) Electron

nt
3. The Higgs boson is responsible for:
a)​ Carrying the electromagnetic force
b)​ Holding quarks together
c)​ Giving particles mass
Ce
ish
d)​ Generating nuclear energy
gl

4. Which particle is a fundamental constituent of matter?

a)​ Gluon b) Quark c) Higgs boson d) Graviton
En

5. What particle mediates the weak nuclear force?

a)​ Photon b) Gluon c) W and Z bosons d) Graviton
E

6 According to the Standard Model, the term "color" refers to:

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a)​ Visible light spectrum

b)​ Charge property of quarks
c)​ Mass of particles
d)​ Spin of particles

7. A particle made up of a quark and an antiquark is called:

a)​ Lepton (b) Baryon (c) Meson (d) Neutrino

8. An elementary particle that feels all three fundamental forces (electromagnetic, weak,
and strong nuclear forces) is:
(a)​ Lepton (b) Quark (c) Electron (d) Neutrino

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9. The primary function of a Geiger-Müller counter in particle physics is to:

a)​ Measure the velocity of particles
b)​ Detect and count ionizing radiation
c)​ Create antimatter particles
d)​ Generate magnetic fields
10. In a Geiger-Müller counter, the gas commonly used to detect ionizing radiation is:
a)​ Oxygen (b) Neon (c) Argon (d) Helium
1)​ c 2)​ c 3)​ c 4)​ b 5)​ c

6)​ b 7)​ c 8)​ b 9)​ b 10)​ c

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Most important Short questions of chapter 28

nt
1.​ Explain the difference between bosons and fermions and their roles in mediating
fundamental forces.

3.​ Explain radiation detector ?

4.​ Briefly explain Wilson cloud Chambers?
Ce
2.​ Explain fundamental forces and their field particles
ish

Most important Numericals of chapter 28

gl

Note: There is no numerical in this chapter

En

Most important Long questions of chapter 28

1.​ Describe the operating principle of a Geiger-Muller counter. How does it detect
E

and quantify ionizing radiation, and what are its limitations in terms of
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measurement.
2.​ Explain the structure of the Standard Model, including the different types of
particles and their relationships. How does the model classify fundamental
forces?

NOTES: Best of Luck 😊

For getting all subject PDF notes and guess paper of classes 9 to 12, contact on
WhatsApp number (0340 8057780) of ME English center
Prepared by: Sir Faiz ur Rehman