Semiconductor D...

Assertion The temperature coefficient of resistance is positive for metals and negative for P-type semiconductor.
Reason The effective charge carriers in metals are negatively charged whereas in P-type semiconductor they are positively charged.

Assertion Electron has higher mobility than hole in a semiconductor.
Reason Mass of electron is less than the mass of hole.

Assertion An N-type semiconductor has a large number of electrons but still it is electrically neutral.
Reason An N-type semiconductor is obtained by doping an intrinsic semiconductor with a pentavalent impurity.

Assertion Light emitting diode (LED) emits spontaneous radiation.
Reason LED are forward biased p-n junctions.

Assertion Silicon is preferred over germanium for making semiconductor devices.
Reason The energy gap for germanium is more than the energy gap of silicon.

Assertion We can measure the potential barrier of a PN-junction by putting a sensitive voltmeter across its terminals.
Reason The current through the PN-junction is not same in forward and reversed bias

Assertion The energy gap between the valence band and conduction band is greater in silicon than in germanium.
Reason Thermal energy produces fewer minority carriers in silicon than in germanium.

Assertion Two P-N junction diodes placed back to back, will work as a NPN transistor.
Reason The P-region of two PN-junction diodes back to back will form the base of NPN transistor

Assertion In transistor common emitter mode as an amplifier is preferred over common base mode.
Reason In common emitter mode the input signal is connected in series with the voltage applied to the base emitter junction.

Assertion The dominant mechanism for motion of charge carriers in forward and reverse biased silicon P-N junction are drift in both forward and reverse bias.
Reason In reverse biasing, no current flows through the junction