Basic Physics II

Assignment for Chapter 22: Electromagnetic Waves

Read chapter 22 by Wednesday, October 28 and Turn in the problems below on Friday, November 6.

1. The magnetic field in a traveling wave has a peak amplitude of 10^-8T. What is the peak amplitude of the electric field?

2. The blackbody radiation from an object peaks (in intensity) at a wavelength given by

where T is in Kelvin.

a) What is the peak wavelength from a source at 300K and what is its frequency?

b) What is the peak wavelength from a source at 5700K and what is its frequency?

3. The electric field in an EM wave has a peak amplitude of 14mV/m.

a) What is the average intensity (Average Power/Area) of the wave?

b) How much energy will pass through a 2m² in one minute?

4. The radiation from the sun reaching the upper atmosphere is about 1400W/m² (this is called the insolation). What is the rms electric field in a wave that would produce this intensity?

5. If the earth is 1.5×10¹¹m from the sun, what is the energy emitted by the sun each second?

6. The speed of an electromagnetic wave in a vacuum is c, but in a material it is given by

where k is the dielectric constant of the material. If the speed of a wave down a cable is 1.5×10⁸m/s, what is the dielectric constant k, for the material in that cable? (Assume m = m_o for the material in the cable.)

We will have an exam after completing chapter 22, probably around November 13.

You will need a large bluebook.