Nuclei — 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.

Consider the energy density in a solenoid at its centre and that near its ends. Which of the two is greater?

Under what condition the force acting on a charge moving through a uniform magnetic field is minimum?

Define neutral point.

The power factor of an a.c. circuit is 0.5. What is the phase difference between voltage and current in the circuit?

Calculate the volume of 1 mole of an ideal gas at STP.

What is the average number of neutrons obtained per nucleus from the fission of uranium nucleus?

Give two factors by which the voltage sensitivity of a moving coil galvanometer can be increased.

Which physical quantity has newton/ampere- meter as unit? Is it scalar quantity or vector quantity?

Name the EM waves used for studying crystal structure of solids. What is its frequency range?