Question

A helium–neon laser produces a beam of diameter 1.75 mm, delivering 1.95  10¹⁸ photons/s. Each photon has a wavelength of 633 nm.

(a) Calculate the amplitude of the electric field inside the beam.
kV/m?

(b) Calculate the amplitude of the magnetic field inside the beam.
µT?

(c) If the beam shines perpendicularly onto a perfectly reflecting surface, what force does it exert on the surface
nN ?

(d) If the beam is absorbed by a block of ice at 0°C for 2.20 h, what mass of ice is melted

g?

Answer 1