Question

the energy stored in a 1.2m length of a laser beam operating at 5 m w will be​

Answer 1

Given:

Length = 1.2 m

Power of the laser beam = 5 mW

To find:

The energy stored in the beam

Calculation:

The energy stored in the beam is given by the formula

U = P×t

Time taken by the wave to travel 1.2 m is

=> t = distance/speed

=> t = 1.2/(3×10⁸)

=> t = 0.4×10⁻⁸ s

By substituting the values in the above formula

=> U = 5×10⁻³×0.4×10⁻⁸

=> U = 2×10⁻¹¹ J

The energy stored in the laser beam is 2×10⁻¹¹ J