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

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

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

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 atomic mass of Uranium `""_92^238"U"` is 238.0508 u, while that of Thorium `""_90^234"Th"` is 234.0436u, and that of Helium `""_2^4"He"` "is 4.0026u. Alpha decay converts `""_92^238"U"` into `""_92^234"Th"` as, shown below:

`""_92^238"U" -> ( ""_90^234"Th" + ""_2^4"He" + "Energy" )`

What is a neutrino?

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)

A thin converging lens of focal length 12 cm is kept in contact with a thin diverging lens of focal length 18 cm. Calculate the effective/equivalent focal length of the combination.

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

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

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

A point object O is placed at a distance of 15cm from a convex lens L of focal length 1 Ocm as shown in Figure 5 below. On the other side of the lens, a convex mirror M is placed such that its distance from the lens is equal to the focal length of the lens. The final image formed by this combination is observed to coincide with the object O. Find the focal length of the convex mirror

In a gamma ray emission from nucleus : 

Calculate the net emf across A and B shown in Figure 1 below :

Write any one use for each of the following mirrors : 

(a) Convex

(b) Concave 

The half-life of radium is 1550 years. Calculate its disintegration constant (`lambda`) .