1: Yo! It's time for the Electromagnetic Plane Wave Boogie! Grab a partner and stand facing one another two arm lengths apart. One of you extend your right arm and point toward your partner with your index finger while the other does the same with the left arm. Your extended index fingers should be almost (but not quite) touching. Now imagine an electromagnetic plane wave coming from behind one of you and passing along that person's arm, then up the partner's arm, through his/her head and on out of the room. Let your fingertips represent the magnitude of the E and B fields as it passes through the plane between you and your partner. One member of the pair should be the E field and one member of the pair should be the B field. When your fingers are at the starting point, the magnitude of the field is zero. If your field is pointing to the right, your finger should be to the right of the starting point … the larger the amplitude the larger the field. Think of a big plane of glass between you and your partner that is perpendicular to your arms. Your fingers will follow the tips of the E and B vectors in that plane of glass as a function of time as the em wave passes through it. Select a direction for the wave and a plane of polarization and start with E=0, B=0. Then do the boogie! Your TA will help you get started. Think about … and understand how it figures into what you do with your fingers … the direction of the em wave, the plane of polarization, the relative amplitudes of E and B, the frequency of the em wave, the relative phase of E and B, and the directions of E and B relative to the direction of the wave propagation.

2: By measuring the electric and magnetic fields at a point in space where there is an electromagnetic wave, can you determine the direction from which the wave came? Explain.

3: An electromagnetic wave has a magnetic field given by

4: The light beam from a searchlight may have an electric-field magnitude of 1000 V/m, corresponding to a potential difference of 1500 B between the head and feet of a 1.5-m-tall person on whom the light is shone. Does this cause the person to feel a strong electric shock? Why or why not?

5: The energy flow to the earth associated with sunlight is about 1.4 kW/m². a) find the maximum values of E and B for a sinusoidal wave with this intensity. b) The distance from the earth to the sun is about 1.5x10¹¹ m. Find the total power radiated by the sun.

6: Most automobiles have vertical antennas for receiving radio broadcasts. Explain what this tells you about the direction of polarization of E in the electromagnetic waves used in radio broadcasting.

7: Electromagnetic radiation is emitted by accelerating charges. The rate at which energy is emitted from an accelerating charge that has charge q and acceleration a is given by

where c is the speed of light.

1. verify this equation is dimensionally correct.
2. Consider the classical hydrogen atom … The electron is a hydrogen atom can be considered to be in a circular orbit with a radius of 0.0529 nm and a kinetic energy of 13.6 eV. If the electron behaved classically, how much energy would it radiate per second? What does this tell you about the usefulness of classical physics to describe atoms?