An atom absorbs a photon of wavelength 500 nm and emits another photon of wavelength 700 nm. Find the net energy absorbed by the atom in the process.

Visible light has wavelengths in the range of 400 nm to 780 nm. Calculate the range of energy of the photons of visible light.

Calculate the momentum of a photon of light of wavelength 500 nm.

Calculate the number of photons emitted per second by a 10 W sodium vapour lamp. Assume that 60% of the consumed energy is converted into light. Wavelength of sodium light = 590 nm.

When the sun is directly overhead, the surface of the earth receives 1.4 × 10³ W m^–2 of sunlight. Assume that the light is monochromatic with average wavelength 500 nm and that no light is absorbed in between the sun and the earth is 1.5 × 10¹¹ m.

(a) Calculate the number of photons falling per second on each square meter of earth’s surface directly below the sun.

(b) How many photons are there is each cubic meter near the earth’s surface at any instant?

(c) How many photons does the sun emit per second?