The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than $$2480$$ $$nm$$ is incident on it. The band gap in $$(eV)$$ for the semiconductor is

In a full wave rectifier circuit operating from $$50$$ $$Hz$$ mains frequency, the fundamental frequency in the ripple would be

In a common base amplifier, the phase difference between the input signal voltage and output voltage is

A piece of copper and another of germanium are cooled from room temperature to $$77K,$$ the resistance of