Question

He-Ne lasers are often used in physics demonstrations. They produce light of wavelength 633nm and a power of 0.650mW spread over a cylindrical beam 1.30mm in diameter (although these quantities can vary).

Part A

What is the intensity of this laser beam?

Part B

What is the maximum value of the electric field?

Part C

What is the maximum value of the magnetic field?

Please any help on how to actually solve this is much appreciated. Thank you again.

Answer 1

Answer 2

the intensity of the beam is I = P / A
P = power of the beam

A = area of cross section of the cilindrical beam

the maximum value of the electric field is

       I = ?oE^2 /2

and the maximum value of the magnetic field

      I = B^2 /2?_o

  

u is the electromagnetic energydensity,

where ?₀ isthe electric constant. The first term in the right-hand siderepresents the net electromagnetic energy flow into a small volume,while the second term represents negative of the work done byelectrical currents that are not necessarily converted intoelectromagnetic energy.

Answer 3

part A: intenisty I = power/area = Emax^2/2uoC

calculate Emax value from there

b. magnetic field B = E/c

c. intensity = Emax^2/2uoC

d. enrgy density u = 0.5 eo E^2