Q. An electron is accelerated through a potential difference of V volt. It has a wavelength λ associated with it. Through what potential difference an electron must be accelerated so that its de Broglie wavelength is the same as that of a proton? Take mass of proton to be 1837 times larger than the mass of electron.
Q. When a metallic surface is illuminated by a light of frequency 8×1014 Hz, photoelectron of maximum energy 0.5eV is emitted. When the same surface is illuminated by light of frequency 12 × 1014 Hz, photoelectron of maximum energy 2eV is emitted. The work function is
Q. A modern 200W sodium street lamp emits yellow light of wavelength 0.6mm. Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is