MCQ
Which of the following has zero average value in a plane electromagnetic wave?
- AKinetic energy
- BMagnetic field
- CElectric field
- DBoth (b) and (©)
✓
Answer
- Both (b) and (©)
Explanation:
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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