Modern Physics - Physics Previous Year Questions

Ground waves have wavelength

In detector, output circuit consists of \(R=10~k\Omega\) and \(C=100~pF\). The frequency of carrier signal which it can detect is

Maximum amplitude of message signal in amplitude modulation is 20 cm. If the amplitude of carrier wave is 40 cm, then modulation index of modulated wave is

The energy gap between valance band and the conduction band for a given material is \(6 \mathrm{~eV}\), then the material is :

The mobility of the charge carriers increases with

The conductivity of a semiconductor increases with increase in temperature because

A) number density of free current carriers increases

B) relaxation time increases

C) both number density of carriers and relaxation time increase

D) number density of current carriers increases, relaxation time decreases but effect of decrease in relaxation time is much less than increase in number density