The Production and Propagation of Electromagnetic Waves – Practice

Questions:

1) Why do power transmission lines produce electromagnetic waves?

2) A radio wave is transmitted at 80 kHz toward a receiving antenna. At what frequency will the electrons oscillate at?

3) A student sets up equipment in a lab to produce and measure radio waves as a current travels through a conductor. Explain why the student observes no electromagnetic radiation using a DC current.

Quick Answers:

1) Transmission lines operate with alternating current (AC). The charges (electrons) in the wire are constantly changing direction and are therefore accelerating. Accelerating charges result in EM radiation. 

2) 80 kHz

3) Accelerating charges result in EM radiation. Charges are not accelerating in a DC circuit.

Worked Answers: