Frequency

• No change: The frequency of light remains constant when it moves from one material to another. This is because frequency is determined by the source of light.

Wavelength

• Changes: The wavelength of light changes depending on the medium. It decreases in denser materials (like glass) and increases in less dense ones (like air).

Speed

• Changes: The speed of light changes when passing through different media. Light travels slower in denser materials and faster in less dense ones. For example, light travels slower in water than in air.

Illustration
When light moves from air to water, its speed and wavelength decrease, but its frequency stays the same.