Question

Assertion: Light year and wavelength have same dimensional formula.

Reason: Both have the dimensions of time.

• A. Both assertion and reason are incorrect
• B. Assertion is correct and reason is incorrect.
• C. Both assertion and reason are correct and reason is the correct explanation for assertion.
• D. Both assertion and reason are correct but reason is not the correct explanation for assertion

Answer 1

The correct option is B

Assertion is correct and reason is incorrect.

The explanation for the assertion:

1. Light year is the distance traveled by light in one year known as light year. It has a unit of length.
2. Dimensional formula is $M^0{L}^1{T}^0$
3. Wavelength is the distance between successive crests in a wave is known as wavelength.
4. It has a unit of length.
5. Dimensional formula is $M^0{L}^1{T}^0$
6. Therefore, both light year and wavelength have the same dimensions.

The explanation for the reason.

1. Since the dimension of light year and wavelength are both $M^0{L}^1{T}^0$, it is clear that they both have the dimension of length.
2. So, both light year and wavelength have the same dimensions which are dimensions of length but not of time.

The given assertion is correct but the reason is wrong.

Hence, the correct answer is option B.