When an electric field is applied across a semiconductor
(a) Electrons move from lower energy level to higher energy level in the conduction band
(b) Electrons move from higher energy level to lower energy level in the conduction band
(c) Holes in the valence band move from higher energy level to lower energy level
(d) Holes in the valence band move from lower energy level to higher energy level

Two 10cm log, straight wires, each carrying a current of 5A are kept parallel to each other. If each wire experienced a force of 10^-5N, then separation between the wires is__________cm.

The positive feedback is required by an amplifier to act an oscillator. The feedback here means:

The variation of acceleration due to gravity (g) with distance (r) from the centre of the earth is correctly represented by: (Given R = radius of earth)

A transistor is used in an amplifier circuit in common emitter mode. If the best current changes by 100 <!-- [if gte mso 9]><xml> </xml><![endif]-->  $\mu A,$ it brings a change of 10 mA is collector current. If the load resistance is 2 $k\Omega$ <!-- [if gte mso 9]><xml> </xml><![endif]--> and input resistance is 1 $k\Omega ,$ <!-- [if gte mso 9]><xml> </xml><![endif]--> the value of power gain is x × 10⁴. The value of x is_____________.

The typical transfer characteristics of a transistor in CE configuration is shown in figure. A load resistor of $2k\Omega$ is connected in the collector branch of the circuit used. The input resistance of the transistor is $0.50k\Omega .$ The voltage gain of the transistor is________.