Magnetism — Physics STD 12 Science — Question

In an n-type silicon, which of the following statement is true :

The focal lengths of the objective and eye-lens of a microscope are 1 cm and 5 cm respectively. If the magnifying power for the relaxed eye is 45, then the length  of the tube is(a)  30 cm(b)  25 cm(c)  15 cm(d)  12 cm

If no external voltage is applied across P-N junction, there would be(a) No electric field across the junction (b) An electric field pointing from N-type to P-type side across the junction(c) An electric field pointing from P-type to N-type side across the junction(d) A temporary electric field during formation of P-N junction that would subsequently disappear

When the light source is approaching, the Doppler effect for light is known as:

In ballistic galvanometer, the frame on which the coil is wound is non-metallic to (a) Avoid the production of induced e.m.f.(b) Avoid the production of eddy currents(c) Increase the production of eddy currents(d) Increase the production of induced e.m.f.

Conductivity of semiconductors:

A copper ring is held horizontally and a bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet while it is passing through the ring is(a) Equal to that due to gravity (b) Less than that due to gravity(c) More than that due to gravity(d) Depends on the diameter of the ring and the length of the magnet

The average binding energy per nucleon in the nucleus of an atom is approximately(a) 8 eV(b) 8 KeV(c) 8 MeV(d) 8 J

As the mass number A increases, the binding energy per nucleon in a nucleus: