PHY2044 - PHYSICS FOR ENGINEERS II
PRACTICE TEST FOR CHAPTER 30

Below you will find a set of 5 conceptual and numerical revision questions selected randomly from lots of questions I have put together covering the material in Chapter 30, "Electromagnetic Waves". This includes questions on the frequency and wavelength of electromagnetic waves, the strength of the E- and B-fields, intensity and radiation pressure. When you have finished the quiz, click on the "Submit Quiz" button at the bottom and within seconds it will be automatically graded and the results returned to you!

To select a new set of questions click on the "Reload" or "Refresh" button on your browser. You may find some of the questions duplicated but that's the nature of a random selection. Try it a few times ... it's not fattening and you may learn something!

Many thanks to Mark Wood for producing the quiz-maker code.


Q1: The peak value of the electric field component of an electromagnetic wave is E. At a particular instant, the intensity of the wave is of 0.020 W/m2. If electric field were increased to 5E, what would be the intensity of the wave?

0.020 W/m2
0.10 W/m2
0.25 W/m2
0.50 W/m2
1.0 W/m2

Q2: An electromagnetic wave has an electric field with peak value 250.0 N/C. What is the average energy delivered to a surface with area 2.00 m2 by this wave in one minute?

83.1 J
166 J
2490 J
4980 J
9960 J

Q3: An electromagnetic wave of intensity 100 W/m2 is incident normally on a square black card whose sides are 25 cm. If the card reflects all of the radiation incident on it, the approximate force exerted by the wave on this card is

64 × 10-9 N
32 × 10-9 N
42 × 10-9 N
10 × 10-9 N
21 × 10-9 N

Q4: The rms value of the magnitude of the magnetic field in an electromagnetic wave is B(rms) = 0.137 T. The intensity of this wave is approximately

2.39 × 1012 W/m2
4.77 × 1012 W/m2
9.54 × 1012 W/m2
2.27 × 1012 W/m2
1.56 × 1012 W/m2

Q5: The figure shows the time variation of the magnitude of the electric field of an electromagnetic wave produced by a wire antenna.

What is the magnitude of the magnetic field at t = 6.67 × 10-10 s?

1.7 × 10-8 T
2.3 × 10-8 T
2.9 × 10-8 T
3.3 × 10-8 T
zero


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