Which statement is true about light and optical density?

Which statement is true about light and optical density?

• A. Light Always Travels at the Same Speed in Every Medium
• B. A Material's Optical Density Affects the Speed of Light Passing Through It
• C. Doubling the Refractive Index Doubles the Light Speed
• D. Angle of Refraction Is Independent of Material

Answer: (B)

Light slows down when it enters a denser material because optical density affects how easily light can propagate. The speed of light in a medium is given by v = c/n, where c is its speed in vacuum and n is the material’s refractive index (a measure of optical density). A higher optical density means a higher refractive index, which reduces the light’s speed. This change in speed also shortens the wavelength inside the medium, while the frequency stays the same as it crosses the boundary. This explains why the statement is true: optical density directly influences how fast light travels through a material. The other ideas don’t fit because light does not retain the same speed in all media, doubling the refractive index does not double speed (it decreases it), and the refraction angle depends on the indices of the two media, not independently of them.

Light slows down when it enters a denser material because optical density affects how easily light can propagate. The speed of light in a medium is given by v = c/n, where c is its speed in vacuum and n is the material’s refractive index (a measure of optical density). A higher optical density means a higher refractive index, which reduces the light’s speed. This change in speed also shortens the wavelength inside the medium, while the frequency stays the same as it crosses the boundary.

This explains why the statement is true: optical density directly influences how fast light travels through a material. The other ideas don’t fit because light does not retain the same speed in all media, doubling the refractive index does not double speed (it decreases it), and the refraction angle depends on the indices of the two media, not independently of them.