Question

Consider the He–Ne laser beam with power P = 0.5 mW, and wavelength in vacuum λo = 632.8 nm, as it travels in the x-direction in an experimental vacuum system at NASA-JPL. Show all work .

a. Knowing that the laser beam intensity, I (W/m^2 ), equals the time average value of the Poynting Vector, Sav= E^2max/2μo^2c , then calculate the maximum amplitude of the electric field for this laser beam.
b. Calculate the magnitude of the magnetic induction, Bmax.

Answer 1

Step-by-step explanation:

Power P = .5 mW = .5 x 10⁻³

P = Emax² / 2μo x c , c is velocity of light , μo is permeability of air .

Emax² = P x 2μo x c

= .5 x 10⁻³ x 2 x 4π x 10⁻⁷ x 3 x 10⁸

= 37.68 x 10⁻²

Emax = 6.14 x 10⁻¹

= .614 v/m

b) Bmax = Emax / c

= .614 / 3 x 10⁸

= .2046 x 10⁻⁸ T

= 20.46 x 10⁻¹⁰ T.