Semiconductor Electronic: Material, Devices And Simple Circuits — Physics STD 12 Science — Question

A glass rod rubbed with silk is used to charge a gold leaf electroscope and the leaves are observed to diverge. The electroscope thus charged is exposed to X-rays for a short period. Then(a) The divergence of leaves will not be affected(b) The leaves will diverge further(c) The leaves will collapse(d) The leaves will melt

Assertion  :  When a tiny circular obstacle is placed in the path of light from some distance, a bright spot is seen at the centre of shadow of the obstacle.
Reason      : Destructive interference occurs at the centre of the shadow. (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 the white light of sun, maximum scattering by the air molecules present in the earth's atmosphere is for:

Two rods of same material and length have their electric resistance in ratio 1 : 2. When both rods are dipped in water, the correct statement will be(a) A has more loss of weight(b) B has more loss of weight(c) Both have same loss of weight(d) Loss of weight will be in the ratio 1 : 2

Cathode rays consist of(a) Photons(b) Electrons(c) Protons(d) α -particles

Which of the following is false for electric lines of force ?

A circular coil of mean radius of 7 cm and having 4000 turns is rotated at the rate of 1800 revolutions per minute in the earth's magnetic field (B = 0.5 gauss), the maximum e.m.f. induced in coil will be(a) 1.158 V(b) 0.58 V(c) 0.29 V           (d) 5.8 V 

The angle between magnetic meridian and geographical meridian is called :