Moving Charges and Magnetism — Physics STD 12 Science — Question

The avalanche breakdown in p-n junction is due to:

Which statement is correct for a zone plate and a lens (a) Zone plate has multi focii whereas lens has one(b) Zone plate has one focus whereas lens has multiple focii(c) Both are correct(d) Zone plate has one focus whereas a lens has infinite

Lightning is a ________ phenomenon:

A p-type semiconductor is:

1. Positively charged.
2. Negatively charged.
3. Uncharged.
4. Uncharged at 0K but charged at higher ternperatures.

Assertion  :  NOT gate is also called inverter circuit.
Reason      : NOT gate inverts the input order.(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.

The equivalent resistance of resistors connected in series is always (a) Equal to the mean of component resistors(b) Less than the lowest of component resistors(c) In between the lowest and the highest of component resistors(d) Equal to sum of component resistors

The quantities remaining constant in a collisions are

1. Momentum, kinetic energy and temperature.
2. Momentum and kinetic energy but not temperature.
3. Momentum and temperature but not kinetic energy.
4. Momentum, but neither kinetic energy nor temperature.

The e.m.f. of a cell is E volts and internal resistance is r ohm. The resistance in external circuit is also r ohm. The p.d. across the cell will be(a) E/2(b) 2E(c) 4E       (d) E/4