A 15.7mW laser beam has a diameter of 4mm. If the amplitude of the associated magnetic field is expressed as \(\frac{A}{\sqrt{\varepsilon_0 c^3}}\), the value of A is:
(𝜀0 is the free space permittivity and 𝑐 is the speed of light)
1
50
2
35.4
3
100
4
70.8