Electromagnetic Waves — Physics STD 12 Science — Question

If the angles of dip at two places are 30^o and 45^o respectively, then the ratio of horizontal  components of earth's magnetic field at the two places will be

(a)

(b) 1 :

(c) 1 :

(d)  1 : 2

All particles of a wave front vibrate:

The diode shown in the circuit is a silicon diode. The potential difference between the points A and B will be

(a) 6 V

(b) 0.6 V

(c) 0.7 V

(d) 0 V

Assertion     :   If the distance between parallel plates of a capacitor is halved and dielectric constant is made three times, then the capacitor becomes 6 times.

Reason        : Capacity of the capacitor does not depend upon the nature of the material.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

In a moving cell galvanometer, we use a radial magnetic field so that the galvanometer scale is:

When there is an electric current through a conducting wire along its length, then an electric field must exist

(a)  Outside the wire but normal to it	(b) Outside the wire but parallel to it
(c) Inside the wire but parallel to it	(d) Inside the wire but normal to it

The photoelectric effect can be understood on the basis of

(a) The principle of superposition	(b) The electromagnetic theory of light
(c) The special theory of relativity	(d) Line spectrum of the atom

The leakage current across a pn junction is due to _________:

The mutual inductance of an induction coil is 5H. In the primary coil, the current reduces from 5A to zero in  . What is the induced emf in the secondary coil

(a) 2500 V

(b) 25000V

(c) 2510V

(d) Zero

Quantisation of charge was experimentally demonstrated by: