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

A circular coil carrying a current I has radius R and number of turns N. If all the three, i.e. the current
I, radius R and number of turns N are doubled, then, the magnetic field at its centre becomes:

(a) Double

(b) Half

(c) Four times

(d) One fourth

Name a material which is used in making control rods in a nuclear reactor.

An emf of 2V is induced in a coil when the current in it is changed from 0A to 10A in 0·40 sec. Find the coefficient of self-inductance of the coil.

Explain the term hysteresis

Obtain an expression for magnetic flux density B at the centre of a circular coil of radius R, having N turns and carrying a current I

With the help of a suitable example and an equation, explain the term pair production.

With what type of source of light are cylindrical wave fronts associated?

A converging lens of focal length 40 cm is kept in contact with a diverging lens of focal length 30 cm. Find the focal length of the combination .

How can the spherical aberration produced by a lens be minimized? 

Two thin lenses having optical powers of -10D and+ 6D are placed in contact with each other. The focal length of the combination is: 

The total energy of an electron in the ground state of the hydrogen atom is -13·6 eV. Its total energy, when a hydrogen atom is in the first excited state, is: 

Write the expression for the Lorentz force F in vector form.

A coil has a self-inductance of 0·05 Henry. Find the magnitude of the emf induced in it when the current flowing through it is changing at the rate of 100 As^-1.

PQ is a long straight conductor carrying a current of 3A as shown in Figure below. An electron moves with a velocity of 2 x 10⁷ ms^-1 parallel to it. Find the force acting on the electron.

Define Curie temperature.

If magnetic susceptibility of a certain magnetic material is 0 0001, find its relative permeability.

State how the focal length of a glass lens (Refractive Index 1.5) changes when it is completely immersed in: 

(i) Water (Refractive Index 1.33)
(ii) A liquid (Refractive Index 1.65)

An object is kept on the principal axis of a concave mirror of focal length 10 cm. at a distance of 15
cm from its pole. The image formed by the mirror is:

(a) Virtual and magnified

(b) Virtual and diminished

(c) Real and magnified

(d) Real and diminished

In Bohr’s model of the hydrogen atom, the radius of the first orbit of an electron is r₀ . Then, the radius of the third orbit is:

a) `r_0/9`

b) `r_0`

c) `3r_0`

d) `9r_0`