When 5V potential difference is applied across a wire of length 0.1, the drift speed of electrons is 2.5× 10^-4m/s if the electron density in the wire is 8× 10²⁸m^-3, calculate the resistivity of the material of wire.

Why can’t we see clearly through fog? Name the phenomenon responsible for it.

A signal of 5kHz frequency is amplitude modulated on a carrier wave of frequency 2MHz. What are the frequencies of the side bands produced?

A proton and an α particle are accelerated through the same potential difference. Which one of the two has (i) greater de- Broglie wavelength, and(ii) less kinetic energy? Justify your answer.

When is H_α line in the emission spectrum of hydrogen atom obtained? Calculate the frequency of the photon emitted during the transition.

OR

Calculate the wavelength of radiation emitted when electron in a hydrogen atom jumps from n=∞ to n=1.