I/GCSE Physics Question Analysis Topic: Physics - Short Questions
Exam Questions:
1) Answer the following
(a) Name the electromagnetic waves which are used for the treatment of certain forms of cancer. Write their frequency range.
(b) Welders wear special glass goggles while working. Why? Explain
(c) Why are infrared waves often called as heat waves? Give their one application.
2) Answer the following
(a) Name the electromagnetic waves which are suitable for radar systems used in aircraft navigation. Write the range of frequency of these waves.
(b) If the earth did not have atmosphere, would its average surface temperature be higher or lower than what it is now? Explain.
(c) An electromagnetic wave exerts pressure on the surface on which it is incident. Justify.
Answers:
For I/GCSE Physics, you should know:
1) (a) Certain types of cancer are treated with the help of gamma rays. The range of the frequencies is 3 x 1019 Hz to 5 x 1024 Hz.
(b) In operation, welders use special glass goggles to shield their eyes from dangerous electromagnetic radiation i.e., UV rays.
(c) Since they induce molecular resonance and increase a substance's internal energy, infrared waves are frequently referred to as heat waves. Burglar alarms, security lighting, TV and DVD player remote controls all make use of such wavelengths.
2) (a) For radar systems used in aircraft navigation, microwaves are suitable. These waves have a frequency range of 109 Hz to 1012 Hz.
(b) There wouldn't be a greenhouse effect on Earth's surface if there were no atmosphere. As a result, the Earth's temperature would drop quickly, making it unlikely for humans to survive.
(c) A linear momentum is carried by an electromagnetic wave. p = U/c gives the linear momentum carried by a part of a wave with energy U.
The wave incident on a material surface will therefore deliver energy U and momentum p = Uc to the surface if it is totally absorbed. The momentum given if the wave is completely reflected is p = 2U/c because the wave's momentum changes from p to -p. Thus, it follows that electromagnetic waves on a surface exert force and hence pressure on said surface.
Work hard for your I/GCSE Physics examination!
End of analysis. Great!
