An instructor’s laser pointer produces a beam of light with a circular cross section of diameter 0.900 mm and a total power output of 4.00 mW. The beam size stays nearly constant when the instructor uses the laser pointer in the classroom. What is the amplitude E 0 of the electric field of the laser’s light? E 0 = N/C What is the amplitude B 0 of the magnetic field of the laser’s light? B 0 = T What is the average energy density u ave of the laser’s light? u ave J/m 3

Explanation:

The Intensity of the beam is

The diameter of the beam is 0.900mm; therefore, the area is

and since , the intensity of the beam is

Now, the intensity is related to by the relation

solving for we get

putting in the numbers we get:

The amplitude of magnetic field is related to by

putting in numerical values we get:

The average energy density of the laser light is

a

explanation:

no diagram was provided, but i'm guessing it's the one i've attached to my answer.

here, a mechanical force turns the rod.   this generates an electric current in the coil, which powers the bulb.

small = small current large mag large current