ISC (Science) ISC Class 12 - CISCE Question Bank Solutions for Physics (Theory)

State any one difference between interference of light and diffraction of light

Laser light of wavelength 630 nm is incident on a pair of slits which are separated by 1.8 mm. If the screen is kept 80 cm away from the two slits, calculate:

1) fringe separation i.e. fringe width.

2) distance of 10^th bright fringe from the centre of the interference pattern

Using the equation `N = N_0e^(-lambdat)` obtain the relation between half-life (T) and decay constant (`lambda`) of a radioactive substance.

 Define critical angle for a given medium. 

An electric current I flows through an infinitely long conductor as shown in Figure 2 (a) below. Write an expression and direction for the magnetic field at point P. 

An electric current I flows through a circular loop as shown in Figure 2(b) below. Write an expression and direction for the magnetic field at the centre of the loop at point P.

Define the following with reference to photoelectric effect : 

(a) Threshold frequency (`f_0`)

(b) Stopping potential (`V_s`)

(i) An alternating emf of 200 V, 50 Hz is applied to an L-R ciruit, having a resistance R of 10 Ω and an  inductance L of 0.05H connected in series. Calculate : 

(1) Impedance

(2) Current flowing in the circuit 

(ii) Draw a labelled graph showing the variation of inductive reactance (`X_L`) verses frequency (`f`) .

Show that electric potential at a point P, at a distance 'r' from a fixed point charge Q, is given by:
    `v=(1/(4pi∈_0))Q/r`.

State Biot Savart law. 

Name the principle on the basis of which optical fibres work.

An alternating emf of 110 V is applied to a circuit containing a resistance R of 80 Ω and an inductor L in series. The current is found to lag behind the supply voltage by an angle 8 = tan^-1 (3/4). Find the :
(i) Inductive reactance
(ii) Impedance of the circuit
(iii) Current flowing in the circuit
(iv) If the inductor has a coefficient of self-inductance of 0.1 H, what is the frequency of the applied emf?

Obtain a relation between the half-life of a radioactive substance and decay constant (λ).

A coil having self-inductance of 0.7 H and resistance of 165 Ω is connected to an a.c. source of 

275V,50Hz. If π = `22/7`

Calculate:
(i) Reactance of the coil
(ii) Impedance of the coil ‘
(iii) Current flowing through the coil 

What are the conditions for obtaining a good interference pattern? Give reasons.

What is meant by Constructive interference?

Explain the following term:

Intrinsic semiconductor

Calculate the minimum amount of energy which a gamma ray photon should have for the production of an electron and a positron pair..

A beam of electrons is used in Young's double-slit experiment. If the speed of electrons is increased then the fringe width will ______.

How will the interference pattern of Young's double slit change if one of the two slits is covered by a paper which transmits only half of the light intensity?