Which list shows electromagnetic waves in order of increasing frequency?
Correct answer: B. Radio waves → infra-red → ultraviolet → gamma rays
- A. Radio waves → gamma rays → ultraviolet → infra-red
- B. Radio waves → infra-red → ultraviolet → gamma rays
- C. Ultraviolet → gamma rays → radio waves → infra-red
- D. Ultraviolet → infra-red → radio waves → gamma rays
Explanation
Electromagnetic waves don't require a medium to travel. They are 7 types, each of them having the same kind of vibrations but different frequencies and wavelengths and hence energies. Cosmic waves are not electromagnetic waves.
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About Alternating Current
Alternating current varies periodically, so phase relationships become essential when current passes through a resistor, capacitor or inductor. The chapter distinguishes resistance from capacitive and inductive reactance, explains phase lead and lag, and connects changing electric and magnetic fields with the production and properties of electromagnetic waves.
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