What happens when light from the Sun passes through any type of matter?

What happens when light from the Sun passes through any type of matter?

• A. The light slows down.
• B. The light speeds up.
• C. Most of the light is absorbed.
• D. Most of the light is reflected.

Answer: (A)

Light slows down in any material compared with its speed in vacuum because the electromagnetic wave interacts with the charged particles inside the medium. This interaction takes time, effectively reducing the wave’s speed. The amount of slowing is described by the material’s refractive index, with v = c/n. So, in air, the slowdown is tiny (n is very close to 1), while in water or glass it’s more noticeable. When light enters a medium, its frequency stays the same, but its wavelength shortens inside the material (since λ = v/f and v is smaller there). Absorption or reflection can occur, but for transparent media most of the light still passes through, just traveling slower. That’s why the general statement is that light slows down.

Light slows down in any material compared with its speed in vacuum because the electromagnetic wave interacts with the charged particles inside the medium. This interaction takes time, effectively reducing the wave’s speed. The amount of slowing is described by the material’s refractive index, with v = c/n. So, in air, the slowdown is tiny (n is very close to 1), while in water or glass it’s more noticeable. When light enters a medium, its frequency stays the same, but its wavelength shortens inside the material (since λ = v/f and v is smaller there). Absorption or reflection can occur, but for transparent media most of the light still passes through, just traveling slower. That’s why the general statement is that light slows down.