Electromagnetic Fields Practice Problems

By — McGraw-Hill Professional
Updated on Sep 18, 2011

Review the following concepts if needed:

Electromagnetic Fields Practice Problems

1. Radio frequency noise caused by lightning in the atmosphere of our planet is called

(a) sferics.

(b) resolution.

(c) aperture.

(d) ground noise.

2. The resolving power of a dish-antenna radio telescope depends largely on

(a) the focal length of the reflector in meters.

(b) the diameter of the reflector in wavelengths.

(c) the distance to the source of the signal.

(d) the gain of the amplifier.

3. When observed at UV compared with visible wavelengths, the Sun

(a) appears brighter.

(b) appears to rotate much more rapidly.

(c) is invisible.

(d) has a larger angular diameter.

4. In order for an EM field to be produced, a charge carrier must be

(a) positive.

(b) negative.

(c) moving.

(d) accelerating.

5. A binary star system, of which one member is a bright visible star and the other member is a black hole orbiting close to the visible star,

(a) radiates virtually all its energy at radio wavelengths.

(b) appears to us as a visible pulsar.

(c) can emit x-rays.

(d) is known as a blackbody.

6. Some radio waves from space cannot reach Earth’s surface because of

(a) the solar wind.

(b) sferics.

(c) the ionosphere.

(d) lack of resolution.

7. The Sun emits most of its EM energy at

(a) radio and IR wavelengths.

(b) IR and visible wavelengths.

(c) visible and UV wavelengths.

(d) UV and x-ray wavelengths.

8. An EM field whose wavelength is 550 nm in free space would appear to us as

(a) a radio wave.

(b) infrared radiation.

(c) visible light.

(d) ultraviolet radiation.

9. The wavelength of greatest EM energy intensity from a blackbody depends on

(a) the distance of the object from Earth.

(b) the angular diameter of the object.

(c) the mass of the object.

(d) the temperature of the object.

10. The radar telescope has been a valuable tool in

(a) the search for life on other worlds.

(b) finding new comets.

(c) observing the surface of Venus.

(d) mapping the radio sky.


1. a

2. b

3. d

4. d

5. c

6. c

7. b

8. c

9. d

10. c

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