NEET
- Exam
- NEET
- Subject
- Physics
- Chapter
- Electromagnetic Waves
NEET · Physics · Electromagnetic Waves
Given below are two statements: one is labelled as Assertion (A)...
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): In a vacuum, the speed of ultraviolet rays is equal to the speed of infrared rays.
Reason (R): Ultraviolet rays have a higher frequency than infrared rays.
In the light of the above statements, choose the most appropriate answer from the options given below:
Assertion (A): In a vacuum, the speed of ultraviolet rays is equal to the speed of infrared rays.
Reason (R): Ultraviolet rays have a higher frequency than infrared rays.
In the light of the above statements, choose the most appropriate answer from the options given below:
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is not correct
- D(A) is not correct but (R) is correct
Correct answer
B. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
Step-by-step solution
In a vacuum, all electromagnetic waves travel with the same speed, , regardless of their wavelength or frequency. Therefore, the speed of ultraviolet rays is equal to the speed of infrared rays. Hence, Assertion (A) is correct.
In the electromagnetic spectrum, the frequency increases in the order: radio waves, microwaves, infrared, visible, ultraviolet, X-rays, and gamma rays. Thus, ultraviolet rays have a higher frequency than infrared rays. Hence, Reason (R) is correct.
However, the higher frequency of ultraviolet rays is not the reason they travel at the same speed as infrared rays. The constant speed of electromagnetic waves in a vacuum is determined by the electric permittivity and magnetic permeability of free space. Therefore, both (A) and (R) are correct but (R) is not the correct explanation of (A).
Answer: Both (A) and (R) are correct but (R) is not the correct explanation of (A)
In the electromagnetic spectrum, the frequency increases in the order: radio waves, microwaves, infrared, visible, ultraviolet, X-rays, and gamma rays. Thus, ultraviolet rays have a higher frequency than infrared rays. Hence, Reason (R) is correct.
However, the higher frequency of ultraviolet rays is not the reason they travel at the same speed as infrared rays. The constant speed of electromagnetic waves in a vacuum is determined by the electric permittivity and magnetic permeability of free space. Therefore, both (A) and (R) are correct but (R) is not the correct explanation of (A).
Answer: Both (A) and (R) are correct but (R) is not the correct explanation of (A)