When light enters a medium with a higher refractive index from air, what happens to the light ray?

When light enters a medium with a higher refractive index from air, what happens to the light ray?

• A. It speeds up.
• B. It bends away from the normal.
• C. It bends toward the normal.
• D. It remains undeviated.

Answer: (C)

When light enters a medium with a higher refractive index, it slows down. Since the frequency stays the same across the boundary, the wavelength shortens in the new medium. Snell’s law tells us that if n2 is greater than n1, then the angle of the ray with respect to the normal must decrease, so the ray bends toward the normal. In other words, moving from air into a denser medium makes the light refract toward the normal because its speed drops, causing the change in direction.

When light enters a medium with a higher refractive index, it slows down. Since the frequency stays the same across the boundary, the wavelength shortens in the new medium. Snell’s law tells us that if n2 is greater than n1, then the angle of the ray with respect to the normal must decrease, so the ray bends toward the normal. In other words, moving from air into a denser medium makes the light refract toward the normal because its speed drops, causing the change in direction.