# When a ray of light enters a glass slab from air

Q: When a ray of light enters a glass slab from air

(A) its wavelength decreases

(B) its wavelength increases

(C) its frequency increases

(D) neither its wavelength nor its frequency changes.

Ans: (A)

Sol: $\large \lambda = \frac{v}{f}$ , ( Where f = frequency)

As frequency remains unchanged , it is a source characteristics .

Since v decreases , wavelength decreases