Question

When light is refracted from air into glass:-
(A) Its wavelength and frequency both increase
(B) Its wavelength increases but frequency remains unchanged
(C) Its wavelength decreases but frequency remains unchanged
(D) Its wavelength and frequency both decrease

Explanation please.
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Answer 1

Explanation:

Its wavelength decrease but frequency remain unchanged.

Answer 2

I think you are familiar with this formula;

• n = c/v
• Refractive index(n) = Velocity of light in vaccum(c)/Velocity of light in medium(v)

And now, the velocity of light(v) in any medium can be calculated from the formula;

• v = f(frequency) λ(wavelength)

Now, see frequency will not change as it depends on the source, so frequency will remain unchanged.

But, what about wavelength? as you can see from formula that, velocity of light is directly proportional to wavelength.

According to question,

• Light travels from air to glass

That is,

• From rarer(air) to denser(glass), ofc its velocity will decrease, ryt?

Finally, as velocity of light is directly proportional to wavelength, thus as in this condition velocity has decreased and so will wavelength.

Atlast, opt c) Its wavelength decreases but frequency remains unchanged is our answer.$\;$