NEET
- Exam
- NEET
- Subject
- Physics
- Chapter
- Electromagnetic Waves
NEET · Physics · Electromagnetic Waves
Assertion (A): In a plane electromagnetic wave propagating in...
Assertion (A): In a plane electromagnetic wave propagating in vacuum, the ratio of the instantaneous magnitudes of the electric and magnetic fields () is always constant and equal to .
Reason (R): In an electromagnetic wave, the electric and magnetic fields oscillate in phase and the ratio of their amplitudes is .
In the light of the above statements, choose the most appropriate answer from the options given below:
Reason (R): In an electromagnetic wave, the electric and magnetic fields oscillate in phase and the ratio of their amplitudes is .
In the light of the above statements, choose the most appropriate answer from the options given below:
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A)
- BBoth (A) and (R) are true but (R) is not the correct explanation of (A)
- C(A) is true but (R) is false
- D(A) is false but (R) is true
Correct answer
A. Both (A) and (R) are true and (R) is the correct explanation of (A)
Step-by-step solution
The instantaneous electric and magnetic fields in a plane electromagnetic wave are given by:
Since the fields oscillate in phase, the sine terms are identical. The ratio of their instantaneous magnitudes is:
Since the ratio of their amplitudes , the instantaneous ratio is also constant and equal to .
Thus, both (A) and (R) are true, and (R) is the correct explanation of (A).
Answer: Both (A) and (R) are true and (R) is the correct explanation of (A)
Since the fields oscillate in phase, the sine terms are identical. The ratio of their instantaneous magnitudes is:
Since the ratio of their amplitudes , the instantaneous ratio is also constant and equal to .
Thus, both (A) and (R) are true, and (R) is the correct explanation of (A).
Answer: Both (A) and (R) are true and (R) is the correct explanation of (A)