Chapter 32: Electromagnetic Waves
1. The moon and the earth are separated by a distance of 384,000km.
a. How much time does it take light to travel this distance?
b. Light from the star Sirius takes 8.61 years to reach earth. How far away is Sirius?
2. A radio station broadcasts at frequency of 830kHz. At some point from the transmitter
the B-field amplitude is 4.82x10-11T.
a. What are the wavelength, wave number, and angular frequency?
b. What is the electric field amplitude?
3. An electromagnetic wave has frequency of 5.7x1014Hz and has speed of 2.17x108m/s in
a piece of glass.
a. What is the wavelength in glass?
b. What is the wavelength in air?
c. What is the index of refraction?
d. What is the dielectric constant for glass?
4. A satellite 2.0x1010m from the sun measures the total intensity of EM radiation to be
a. If the sun radiates uniformly in all directions what is the total average power
b. If the satellite was at half the distance how would the intensity change?
5. What happens to intensity if the E-field amplitude doubles? What happens to the B-field
6. And intense light source radiates uniformly in all directions. At a distance of 5.0m from
the source the radiation pressure on a perfectly absorbing surface is 9.0x10-6Pa.
a. What is the total average power?
b. What is the radiation pressure for a perfectly reflecting surface?