Electromagnetic Induction — Physics STD 12 Science — Question

What is the resistivity of a pure semiconductor at absolute zero?

To use a transistor as an amplifier, emitter-base junction is kept in ...X... and base-collector junction is kept in ...Y... Here, X and Y refer to:

The depletion layer in the P-N junction region is caused by

(a) Drift of holes	(b) Diffusion of charge carriers
(c) Migration of impurity ions	(d) Drift of electrons

An LC resonant circuit contains a 400 pF capacitor and a 100 mH inductor. It is set into oscillation coupled to an antenna. The wavelength of the radiated electromagnetic waves is

(a) 377 mm

(b) 377 metre

(c) 377 cm

(d) 3.77 cm

The thickness of the depletion region is of the order of ___________ of a micrometre.

One a.m.u is defined as mass of:

In Einstein’s picture of Photoelectric emission, the photoelectric emission does not take place by:

Consider a vehicle going on a horizontal road towards east. Neglect any force by the air. The frictional forces on the vehicle by the road:

1. Is towards east if the vehicle is accelerating.
2. Is zero if the vehicle is moving with a uniform velocity.
3. Must be towards east.
4. Must be towards west.

A cell of internal resistance r is connected to an external resistance R. The current will be maximum in R, if

(a) R = r

(b) R < r

(c) R > r

(d) R = r/2

A thin lens made of glass of refractive index 1.5 has a front surface + 11 D power and back surface – 6 D. If this lens is submerged in a liquid of refractive index 1.6, the resulting power of the lens is

(a) – 0.5 D

(b) + 0.5 D

(c) – 0.625 D

(d) + 0.625 D