MCQ
Which of the following has zero average value in a plane electromagnetic wave?
- AKinetic energy
- BMagnetic field
- CElectric field
- ✓Both $(b)$ and $(©)$
✓
Answer
Correct option: D.
Both $(b)$ and $(©)$
The average of $\sin\theta$ and $\cos\theta$ for whole cycle is is zero.
Step $1:$ Analyzing the average value of Kinetic energy.
Kinetic Energy is always a positive quantity, therefore its average will also be a positive quantity.
Step $2:$ Finding the average of electric and the magnetic field.
The equations for the electric field and the magnetic field are given as
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