Question

When light waves travel from rarer medium to denser medium, the quantities which get changed are

• A. velocity and frequency.
• B. frequency and amplitude.
• C. velocity and wavelength.
• D. frequency and wavelength.

Hint:

Frequency is set by the source and stays constant across a boundary, while speed and wavelength change with the medium.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept
When light passes from one medium to another, its frequency stays the same because it is fixed by the source.
The speed of light depends on the refractive index of the medium: \(v=\dfrac{c}{\mu}\).

Step 2: Effect of a Denser Medium
A denser medium has a larger refractive index \(\mu\), so the speed of light \(v\) decreases.

Step 3: Effect on Wavelength
Since \(v=f\lambda\) and \(f\) is constant, a smaller \(v\) means a smaller wavelength \(\lambda\).

Step 4: Conclusion
So velocity and wavelength change, while frequency does not.

Final Answer:
Velocity and wavelength change when light goes from a rarer to a denser medium. \[ \boxed{\text{(C) }\text{velocity and wavelength}} \]