BISE Lahore · Class 12 · Physics

BISE Lahore · Class 12 · Physics · 2025 · First Annual · Group 1 · Code 8471

2025 · First Annual

Transcribed from the identified examination paper. Check the board, session and course before use. SchoolOrbit is not affiliated with the issuing board.

Objective

Source code: 8471 · Printed marks: 17 · Time: 20 Minutes

Lahore Board Group-I (First Annual Examination 2025)
PHYSICS
INTER PART - II
225-1st Annual
Group - I
Paper - II (Objective Type)
Academic Sessions 2021 - 2023 & 2023 - 2025

1

NOTE: Four possible answers A, B, C and D to each question are given. The choice which you think is correct, fill that circle in front of that question with Marker or Pen ink in the answers book. Cutting or filling two or more circles will result in zero mark in that question.

1
The statement that the flux through any closed surface is $\frac{1}{ε_{o}}$ time the total charge enclosed in it was given by:
- (A)
  Plank
- (B)
  Maxwell
- (C)
  Faraday
- (D)
  Gauss
2
In case of capacitor, for energy density is given by:
- (A)
  $\frac{1}{2} ε_{r} ε_{o} E^{2} A d$
- (B)
  $\frac{1}{2} ε_{r} ε_{o} E^{2} A d$
- (C)
  $\frac{1}{2} ε_{r} E^{2}$
- (D)
  $\frac{1}{2} ε_{o} E^{2}$
3
The device which converts heat energy into electrical energy is:
- (A)
  Thermocouple
- (B)
  Solar cell
- (C)
  Electric generator
- (D)
  Cell
4
Torque produces in a current carrying coil when it is placed in:
- (A)
  Gravitational field
- (B)
  Electric field
- (C)
  Magnetic field
- (D)
  Nuclear field
5
Shunt resistance of an ammeter is:
- (A)
  $R_{s} = \frac{I - I_{g}}{I_{g}} R_{g}$
- (B)
  $R_{s} = (I - I_{g}) R_{g}$
- (C)
  $R_{s} = \frac{I_{g}}{R_{g}}$
- (D)
  $R_{s} = \frac{I_{g}}{I - I_{g}} R_{g}$
6
One henry is equal to:
- (A)
  $V S^{- 1} A^{- 1}$
- (B)
  $V S A^{- 1}$
- (C)
  $V S^{- 1} A$
- (D)
  $V S A$
7
A device which converts electrical energy into mechanical energy is called:
- (A)
  Transformer
- (B)
  D.C. generator
- (C)
  A.C. generator
- (D)
  D.C. motor
8
The frequency of an inductor of $1.0 H$ have a reactance of $500 Ω$ is:
- (A)
  $70 H z$
- (B)
  $80 H z$
- (C)
  $90 H z$
- (D)
  $100 H z$
9
The A.M. transmission frequencies range is from:
- (A)
  $540 μ H z$ to $1600 μ H z$
- (B)
  $540 K H z$ to $1600 K H z$
- (C)
  $540 M H z$ to $1600 M H z$
- (D)
  $540 H z$ to $1600 H z$
10
The curie temperature for iron is about:
- (A)
  $75^{\circ} C$
- (B)
  $750^{\circ} C$
- (C)
  $7500^{\circ} C$
- (D)
  $75000^{\circ} C$
11
In a certain circuit, the transistor has a collector of $10 m A$ and a base current of $40 μ A$ . The current gain of the transistor is:
- (A)
  $250$
- (B)
  $300$
- (C)
  $350$
- (D)
  $450$
12
Output resistance of an operational amplifier is:
- (A)
  A few ohms
- (B)
  Mili ohms
- (C)
  Mega ohms
- (D)
  Micro ohms
13
When platinum wire is heated, it appears white at about:
- (A)
  $500^{\circ} C$
- (B)
  $900^{\circ} C$
- (C)
  $1100^{\circ} C$
- (D)
  $1600^{\circ} C$
14
The Davisson and Germer experiment confirmed:
- (A)
  Wave nature of particles
- (B)
  Polarization
- (C)
  Compton effect
- (D)
  Photoelectric effect
15
An atom can reside in metastable state for:
- (A)
  $\sim 10^{- 6} s$
- (B)
  $\sim 10^{- 5} s$
- (C)
  $\sim 10^{- 4} s$
- (D)
  $\sim 10^{- 3} s$
16
One twelveth the mass of carbon atom is:
- (A)
  $1 u = 1.6606 \times 10^{- 31} k g$
- (B)
  $1 u = 1.6606 \times 10^{- 27} k g$
- (C)
  $1 u = 1.6606 \times 10^{- 15} k g$
- (D)
  $1 u = 1.6606 \times 10^{- 6} k g$
17
The dead time of the G.M. counter is:
- (A)
  $\sim 10^{- 8} s$
- (B)
  $\sim 10^{- 6} s$
- (C)
  $\sim 10^{- 4} s$
- (D)
  $\sim 10^{- 3} s$

Subjective

These versions contain different content. Choose the source edition you need; they are alternatives, not consecutive exam sections.

Original scanned paper

Printed marks: 68 · Time: 2:40 hours

PHYSICS
INTER PART - II
225-1st Annual
Group - I
Paper - II (Essay Type)
Academic Sessions 2021 - 2023 & 2023 - 2025

SECTION - I

2

Write short answers to any EIGHT (8) questions:
16

(i)
How can you identify that which plate of a capacitor is positively charged?
(ii)
Electric lines of force never cross. Why?
(iii)
Describe the effect of medium between two charges upon the Coulomb's force.
(iv)
What was the result of Millikan oil drop experiment?
(v)
How can a current loop be used to determine the presence of a magnetic field in a given region of space?
(vi)
How lamp and scale arrangement is used to observe angle of deflection in galvanometer?
(vii)
What is digital multimeter? What is its advantage?
(viii)
Why the voltmeter should have a very high resistance?
(ix)
A particle which produces more ionization is less penetrating. Why?
(x)
What information is revealed by the length and shae of the tracks of an incident particle in Wilson Cloud Chamber?
(xi)
Why are thermal reactors called "thermal"? How do they differ from fast reactors?
(xii)
Define mass defect and binding energy.

3

Write short answers to any EIGHT (8) questions:
16

(i)
How does the motion of electrons in a n-type substance differ from motion of holes in a p-type substance?
(ii)
How does electron-hole pairs produce current in a photo-voltaic cell?
(iii)
Explain with the circuit diagram, how a transistor acts as an ON switch?
(iv)
Why orderliness of domains of a ferromagnetic material is not preserved at high temperature? Explain.
(v)
How many crystal system exist based on geometrical arrangement? Draw schematics of any two systems.
(vi)
What is meant by hysteresis loss? How is it used in construction of a transformer?
(vii)
How many times per second will an incandescent lamp reach maximum brilliance when connected to a $50 H z$ source?
(viii)
In an RL circuit, will the current lag or lead the voltage? Illustrate your answer by a vector diagram.
(ix)
In an ideal parallel resonant circuit, why source current is zero at resonant frequency?
(x)
What do you mean by drift velocity? What is the effect on the drift velocity by increasing the potential difference?
(xi)
State Kirchhoff's first rule. Interpret it as law of conservation of electric charge.
(xii)
Differentiate between ohmic and non-ohmic devices. Give one example of each.

4

Write short answers to any SIX (6) questions:
12

(i)
How would you position a flat loop of wire in a changing magnetic field so there is no emf induced in the loop?
(ii)
Can a D.C. motor be turned into a D.C. generator? What changes are required be done?
(iii)
What is back emf effect in motor?
(iv)
When does light behave as a wave when does it behave as a particle?
(v)
What happens to total radiations from black body if its absolute temperature is doubled?
(vi)
What is general theory of relativity?
(vii)
State and write formula of Compton effect.
(viii)
Is energy conserved when an atom emits a photon of light?
(ix)
Define ionization potential and excitation potential.

SECTION - II

Note: Attempt any THREE questions.

5(a)
Define electric potential difference and absolute electric potential. Also derive the relation between electric field and electric potential gradient such that $\overset{ˉ}{E} = - \frac{Δ v}{Δ r}$ .
(5)
5(b)
The resistance of an iron wire at $0^{\circ} C$ is $1 \times 10^{4} Ω$ . What is the resistance at $500^{\circ} C$ , if the temperature coefficient of resistance of iron is $5.2 \times 10^{- 3} K^{- 1}$ ?
(3)
6(a)
Derive the relation for energy stored in an inductor in terms of magnetic field.
(5)
6(b)
A power line $10 m$ high carries a current of $200 A$ . Find the magnetic field of the wire at the ground.
(3)
7(a)
What is rectification? Discuss the phenomenon of semiconductor diode as full wave rectifier.
(5)
7(b)
Find the value of current and inductive reactance when A.C voltage of $200 V$ at $50 H z$ is passed through an inductor of $10 H$ .
(3)
8(a)
Define and explain photoelectric effect. Also explain photoelectric effect on the basis of quantum theory.
(5)
8(b)
A $1.25 c m$ diameter cylinder is subjected to a load of $2500 k g$ . Calculate the stress on the bar in mega pascals.
(3)
9(a)
Explain experimental arrangement for the production of X-rays. What are characteristic X-rays? Discuss spectrum of X-rays.
(5)
9(b)
Calculate the energy (in Mev) released in the reaction $_{1}^{2} H +_{1}^{3} H \to_{2}^{4} H e +_{0}^{1} n$ mass of $_{1}^{2} H$ , $2.014102 u$ , $_{1}^{3} H$ , $3.01605 u$ , $_{0}^{1} n$ , $1.008665 u$ and $_{2}^{4} H e$ , $4.002603 u$ .
(3)

Earlier publisher reprint

Printed marks: 68 · Time: 2.40 hrs.

UNSOLVED

Physics

Inter Part-II, 2025

Lahore Board

Group – I

Essay Type

SECTION – I

Q.2

Write short answers to any EIGHT (8) questions:

i
How can you identify that which plate of a capacitor is positively charged?
ii
Electric lines of force never cross. Why?
iii
Describe the effect of medium between two charges upon the Coulomb's force.
iv
What was the result of Millikan oil drop experiment?
v
How can a current loop be used to determine the presence of a magnetic field in a given region of space?
vi
How lamp and scale arrangement is used to observe angle of deflection in galvanometer?
vii
What is digital multimeter? What is its advantage?
viii
Why the Voltmeter should have a very high resistance?
ix
A particle which produces more ionization is less penetrating. Why?
x
What information is revealed by the length and shape of the tracks of an incident particle in Wilson Cloud Chamber?
xi
Why are thermal reactors called "thermal"? How do they differ from fast reactors?
xii
Define mass defect and binding energy.

Q.3

Write short answers to any EIGHT (8) questions:

i
How does the motion of electrons in a n-type substance differ from motion of holes in a p-type substance?
ii
How does electron-hole pairs produce current in a photo-voltaic cell?
iii
Explain with the circuit diagram, how a transistor acts as an ON switch?
iv
Why orderliness of domains of a ferromagnetic material is not preserved at high temperature? Explain.
v
How many crystal systems exist based on geometrical arrangement? Draw schematics of any two systems.
vi
What is meant by hysteresis loss? How is it used in construction of a transformer?
vii
How many times per second will an incandescent lamp reach maximum brilliance when connected to a $50 H z$ source?
viii
In an RL circuit will the current lag or lead the voltage? Illustrate your answer by a vector diagram.
ix
In an ideal parallel resonant circuit, why source current is zero at resonant frequency?
x
What do you mean by drift velocity? What is the effect on the drift velocity by increasing the potential difference?
xi
State Kirchhoff's first rule. Interpret it as law of conservation of electric charge.
xii
Differentiate between ohmic and non-ohmic devices. Give one example of each.

Q.4

Write short answers to any SIX (6) questions:

i
How would you position a flat loop of wire in a changing magnetic field so there is no emf induced in the loop?
ii
Can a D.C. motor be turned into a D.C. generator? What changes are required be done?
iii
What is back emf effect in motor?
iv
When does light behave as a wave when does it behave as a particle?
v
What happens to total radiations from black body if its absolute temperature is doubled?
vi
What is general theory of relativity?
vii
State and write formula of Compton effect.
viii
Is energy conserved when an atom emits a photon of light?
ix
Define ionization potential and excitation potential.

SECTION – II

Note: Attempt any THREE questions.

Q.5
(a)
Define electric potential difference and absolute electric potential. Also derive the relation between electric field and electric potential gradient such that $\overset{ˉ}{E} = \frac{Δ v}{Δ r}$ .
(5)
(b)
The resistance of an iron wire at $0^{\circ} C$ is $1 \times 10^{4} Ω$ . What is the resistance at $500^{\circ} C$ , if the temperature coefficient of resistance of iron is $5.2 \times 10^{- 3} K^{- 1}$ ?
(3)
Q.6
(a)
Derive the relation for energy stored in an inductor in terms of magnetic field.
(5)
(b)
A power line $10 m$ high carries a current of $200 A$ . Find the magnetic field of the wire at the ground.
(3)
Q.7
(a)
What is rectification? Discuss the phenomenon of semiconductor diode as full wave rectifier.
(5)
(b)
Find the value of current and inductive reactance when A.C voltage of $200 V$ at $50 H z$ is passed through an inductor of $10 H$ .
(3)
Q.8
(a)
Define and explain photoelectric effect. Also explain photoelectric effect on the basis of quantum theory.
(5)
(b)
A $1.25 c m$ diameter cylinder is subjected to a load of $2500 k g$ . Calculate the stress on the bar in mega pascals.
(3)
Q.9
(a)
Explain experimental arrangement for the production of X-rays. What are characteristic X-rays? Discuss spectrum of X-rays.
(5)
(b)
Calculate the energy (in Mev) released in the reaction $_{1}^{2} H +_{1}^{3} H ⟶_{2}^{4} H e +_{0}^{1} n$ Mass of $_{1}^{2} H$ , $2.014102 u$ , $_{1}^{3} H$ , $3.01605 u$ , $_{0}^{1} n$ , $1.008655 u$ and $_{2}^{4} H e$ , $4.002603 u$
(3)

Original source references (3)

The original files and numbering are retained. Equivalent files do not repeat the questions above.

Objective · 8471 · Printed marks: 17 · Time: 20 Minutes
Subjective · psp_1fb9b7f634d1960a16a180fdd079ee55 · Printed marks: 68 · Time: 2:40 hours
Subjective · psp_ebafc60830038346ee2a58cbcc87f26a · Printed marks: 68 · Time: 2.40 hrs.