Electric Charges and Fields — Physics STD 12 Science — Question

A convex lens of crown glass (n =1.525) will behave as a divergent lens if immersed in(a) Water (n = 1.33)(b) In a medium of n = 1.525(c) Carbon disulphide n = 1.66(d) It cannot act as a divergent lens

A person's near point is 50 cm and his far point is 3 m. Power of the lenses he requires for
(i)  reading and  (ii) for seeing distant stars are(a) – 2 D and 0.33 D(b) 2 D and – 0.33 D(c) – 2 D and 3 D(d) 2 D and – 3 D

A transistor is used in common emitter mode as an amplifier. Then(a) The base-emitter junction is forward biased(b) The base-emitter junction is reverse biased(c) The input signal is connected in series with the voltage applied to the base-emitter junction(d) a, c

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 

What should be the angle between two plane mirrors so that whatever be the angle of incidence, the incident ray and the reflected ray from the two mirrors be parallel to each other(a) 60°(b) 90°(c) 120°(d) 175°

A body has its centre of mass at the origin. the x-coordinates of the particles:

1. May be all positive.
2. May be all negative.
3. May be all non-negative.
4. May be positive for some cases and negative in other cases.

When sound wave is refracted from air to water, which of the following will remain unchanged?

1. Wave number.
2. Wavelength.
3. Wave velocity.
4. Frequency.

The nature of effective nuclear forces is :

Davission and Germer experiment proved(a) Wave nature of light (b) Particle nature of light (c) Both (a) and (b) (d) Neither (a) nor (b)