High power laser has a beam diameter of 1 mm and generates an electric field with an amplitude of 0.9 MV/m at the target. Find the average power of the laser. a) 511 W b) 845 W c) 700 W d) 667 W e) 1040 W

b) 845 W

Explanation:

Diameter = 1 mm

E = Electric field = 0.9 MV/m

Average power = Intensity (I) * Area (A)

Intensity

I = 0.5ε₀E²c

ε₀ = 8.85*10⁻¹² F/m

c = 3*10⁸ m/s

I = 0.5 * 8.85*10⁻¹² * (0.9*10⁶) ² * 3*10⁸

Area

A = πr² = π0.5²*10⁻⁶

Average power = 0.5 * 8.85*10⁻¹² * (0.9*10⁶) ² * 3*10⁸ * π0.5²*10⁻⁶ = 844.5190

Average power of the laser is 845 W