Geometrical Optics — Physics STD 12 Science — Question

Which of the following statement regarding transformer is incorrect?

Soap bubbles appear colored when seen in white light. The reason for this phenomenon is :

A current passes through a wire of non-uniform cross-section. Which of the following quantities are independent of the cross-section?

Light waves are:

Unit of electromotive force :

According to Bohr, only those states are stable, in which angular momentum of electron will be :

A sphere of radius R has a uniform distribution of electric charge in its volume. At a distance x from its centre, for x < R, the electric field is directly proportional to

(a)

(b)

(c) x

(d)

The resistance  of a conductor varies with temperature t as shown in the figure. If the variation is represented by  = , then

(a) α  and  β are both negative	(b) α and β are both positive
(c) α is positive and β is negative	(d) α is negative and β are positive

A very small magnet is placed in the magnetic meridian with its south pole pointing north. The null point is obtained 20 cm away from the centre of the magnet. If the earth's magnetic field (horizontal component) at this point be 0.3 gauss, the magnetic moment of the magnet is

(a) 8.0

(b) 1.2

(c) 2.4

(d) 3.6

Which among the following cannot be the charge of a charged body?