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

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.