Question

A high-energy pulsed laser emits a 1.0-ns-long pulse of average power 6.7×10¹¹ W . The beam is 2.1×10−3m in radius.

A) Determine the energy delivered in each pulse. (In J)

B) Determine the rms value of the electric field. (In V/m)

Answer 1

A.)

Energy is given by,

U = Power(P)*time(t)

given, P = 6.7*10^11 W

t = time = 1.0 ns =1.0*10^-9

So, U = (6.7*10^11)*(1.0*10^-9)

U = 670 J

B.)

rms value of the electric field will be:

Erms = sqrt(*c*I)

here, I = intensity = P/A

c = apeed of light = 3*10^8 m/s

= 4*pi*10^-7

A = area = pi*r^2

r = 2.1*10^-3 m

So,

Erms = sqrt[(4*pi*10^-7)*(3*10^8)*(6.7*10^11)/(pi*(2.1*10^-3)^2)]

Erms = 4.27*10^9 V/m