Alternating Current — Physics STD 12 Science — Question

When a semiconducting material is doped with an impurity, new acceptor levels are created. In a particular thermal collision, a valence electron receives an energy equal to 2kT and just reaches one of the acceptor levels. Assuming that the energy of the electron was at the top edge of the valence band and that the temperature T is equal to 300K, find the energy of the acceptor levels above the valence band.

Choose the correct alternative from the clues given at the end of the each statement:
In the ground state of .......... electrons are in stable equilibrium, while in .......... electrons always experience a net force. (Thomson’s model/ Rutherford’s model.)

If the speed of a transverse wave on a stretched string of length 1m is 60m/s, what is the fundamental frequency of vibration?

What is the net magnetic moment of atom of diamagnetic substance?

The density of a rod AB continuously increases from A to B. Is it easier to set it in rotation by clamping it at A and applying a perpendicular force at B or by clamping it at B and applying the force at A?

When a dielectric slab is gradually inserted between the plates of an isolated parallel-plate capacitor, the energy of the system decreases. What can you conclude about the force on the slab exerted by the electric field?

A small creature moves with constant speed in a vertical circle on a bright day. Does its shadow formed by the sun on a horizontal plane move in a simple harmonic motion?

Define the term 'activity' of radionuclide. Write its SI unit.

Define intensity of magnetisation.

If the speed of a particle moving. at a relativistic speed is doubled, its linear momentum will:

1. Become double.
2. Become more than double.
3. Remain equal.
4. Become leas than double.