Question

1) The average intensity of electromagnetic waves at a certain point is 500 W/m2. What is the amplitude of the wave's electric field.

a. 265 V/m b. 449 V/m c. 614 V/m d. 736 V/m

2) What is the radiation momentum density of an electromagnetic wave having an electric field amplitude of 1000 V/m and travelling in a vacuum?

a. 4.07 x 10^-15 kg m-2 s-1 b. 9.28 x 10^ -15 c. 1.48 x 10^-14 d. 6.25 x 10^-13

3) A lightning bolt may carry a current of 1.50 x 10⁴ A for a short period of time. Supposing that the bolt extends far above and below the point of observation, what is the resulting magnetic field 100 m from the bolt?

a. 15 mT b. 30 mT c. 45 mT d. 60 mT

Answer 1