What is a key factor that determines the bending of light during refraction?

• A. Wavelength of the light
• B. Speed of light in a vacuum
• C. Refractive index of the materials involved
• D. Angle of incidence

Answer: (C)

The bending of light during refraction is primarily determined by the refractive index of the materials involved. The refractive index is a dimensionless number that describes how fast light travels in a medium compared to how fast it travels in a vacuum. When light passes from one medium to another — for example, from air into water — its speed changes, which in turn causes the light to bend. This bending is described by Snell's law, which states that the angle of incidence and refraction are related by the ratio of the sine of these angles to the refractive indices of the two media.

The refractive index accounts for the optical density of the materials: a higher refractive index indicates that light travels slower in that medium, leading to greater bending when entering or exiting that medium. Therefore, understanding the refractive indices of the involved materials provides crucial insight into how much the light will bend as it refracts.