Answer:
4
Explanation:
Refraction is the bending of light when it moves from one medium to another.
In the situation described:
- The average speed of light changes when it goes to another medium. The speed of light in water is less than in air.
- When velocity/speed changes, the index of refraction changes as well. Water's index is greater than in air.
- Since, speed changes, wavelength changes too.
- Only the frequency remains the same. The rates of vibration stays the same.
Correct choice is #4.