Electromagnetic Waves - Result Question 9
9. The ratio of amplitude of magnetic field to the amplitude of electric field for an electromagnetic wave propagating in vacuum is equal to :
(a) the speed of light in vacuum [2012M]
(b) reciprocal of speed of light in vacuum
(c) the ratio of magnetic permeability to the electric susceptibility of vacuum
(d) unity
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Answer:
Correct Answer: 9. (b)
Solution:
- (b) The average energy stored in the electric
field,
The average energy stored in the magnetic field
According to conservation of energy
The average energy density of electric field
Thus, the average energy density of electric field equal to the average density of magnetic field.
