BISE Sargodha · Class 12 · Physics

BISE Sargodha · Class 12 · Physics · 2025 · Group 2 · Subjective

2025

Source total marks: 68 Time allowed: 2.40 hours

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

1225

Warning:- Please, do not write anything on this question paper except your Roll No.

Physics (Subjective)

Group II

(Inter Part-II)

Paper (II)

(Session2021-23to2023-25)

Time Allowed: 2.40 hours

Maximum Marks: 68

Section I

2.

Answer briefly any Eight parts from the followings:-

8 × 2 = 16

(i)
Write down the properties of electric field lines? Any two
(ii)
Is $E$ necessarily zero inside a charged rubber balloon if balloon is spherical? Assume that charge is distributed uniformly over the surface?
(iii)
Do electrons tend to go to region of high potential or of low potential?
(iv)
What is the effect of dielectric medium on electric force? When it is placed between two point charges?
(v)
What should be the orientation of a current carrying coil in a magnetic field so that torque acting upon the coil is maximum?
(vi)
How can you use a magnetic field to separate isotops of chemical element?
(vii)
Suppose that a charge $q$ is moving in a uniform magnetic field with a velocity $v$ . Why is there no work done by the magnetic force acts on the charge $q$ ?
(viii)
How fast must be a proton moving in a magnetic field of $2.50 \times 10^{- 3}$ . Such that the magnetic force and weight are equal?
(ix)
What factors make a fusion reaction difficult to achieve?
(x)
What do we mean by term critical mass?
(xi)
If someone accidently swallows an $α$ -source and a $β$ -source which would be the more dangerous to him? Explain why?
(xii)
Distinguish between Nuclear Fission and Nuclear Fusion?

3.

Answer briefly any Eight parts from the followings:-

8 × 2 = 16

(i)
Do bends in a wire affect its electrical resistance? Explain.
(ii)
Why does resistance of a conductor rise with temperature?
(iii)
What is the difference between e.m.f and terminal potential difference?
(iv)
How many times per second will an incandescent bulb reaches the maximum brilliance when connected to a $50 H z$ source?
(v)
In RL-circuit, will the current lag or lead the voltage, show by vector diagram.
(vi)
Define the term impedance with units.
(vii)
Why glass is called solid liquid?
(viii)
Define an "energy band".
(ix)
What is meant by hysteresis loss?
(x)
Why photo diode is used in reverse biase?
(xi)
Write down the truth table for NAND Gate.
(xii)
Why ordinary silicon diode do not emit light?

4.

Answer briefly any Six parts from the followings:-

6 × 2 = 12

(i)
How would you position a flat loop of wire in a changing magnetic field so that there is no emf induced in the loop?
(ii)
In a certain region the earth's magnetic field points vertically down. When a plane flies due north, which wingtip is positively charged?
(iii)
Write the factors on which mutual inductance depends.
(iv)
A beam of red light and a beam of blue light have exactly the same energy. Which beam contains the greater number of photons?
(v)
Is it possible to create a single electron from energy? Explain.
(vi)
Calculate the de-Broglie wavelength associated with proton moving at $40 m s^{- 1}$ (mass of proton $= 1.67 \times 10^{- 27} K g$ )
(vii)
Write any four applications of photocell.
(viii)
Define spectroscopy. Also write the types of spectra.
(ix)
What is meant by line spectrum? Explain, how line spectrum can be used for the identification of elements.

Section II

Note: Attempt any three questions.

8 × 3 = 24

5.
(a)
State Gauss's law. How can you apply the Gauss's law to calculate electric intensity due to an infinite sheet of charge?
(b)
How many electrons pass through an electric bulb in one minute if the $300 m A$ current is passing through it?
6.
(a)
State Ampere's law and write mathematical form. Apply it to find magnetic field inside a solenoid.
(b)
An ideal step down transformer is connected to main supply of $240 V$ . It is desired to operate a $12 V$ , $30 W$ lamp. Find the current in the primary and the transformation ratio.
7.
(a)
Draw RLC parallel circuit. Find its Impedence diagram and resonance frequency. Give its any two properties?
(b)
The current flowing into the base of a transistor is $100 μ A$ . Find its collector current $I_{C}$ its emitter current $I_{E}$ and the ratio $I_{C} / I_{E}$ . If the value of current gain $β$ is $100$ .
8.
(a)
Define intrinsic and extrinsic semiconductors. Also explain n-type and p-type substances.
(b)
What is the de Broglie wavelength of an electron whose Kinetic energy is $120 e V$ ?
9.
(a)
What is laser? Describe its principle and operation briefly.
(b)
How much energy is absorbed by a man of mass $80 k g$ who receives a lethal whole body equivalent dose of $400 r e m$ in the form of low energy neutron for which RBE factor is $10$ ?
1228--1225SGD--15000