Assertion Focal length of a lens depends on the wavelength of light used.
Reason The more the wavelengths, lesser is the focal length.

Options

A. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
B. If both Assertion and Reason are true but Reason is not correct explanation of Assertion.
C. If Assertion is true but Reason is false.
D. If Assertion is false but Reason is true.

Answer

C

Explanation

(c) If `lamda`. is more, then `mu` will be less as per Cauchy's formula `mu=(A+B)/(lamda^(2))`. Therefore, focal length will be more.