Refraction and Lenses Practice Test

Dispersion is the idea: white light is made of many wavelengths, and a transparent material can bend each wavelength by a different amount. A prism, usually a triangular glass piece, uses this property. As light enters and leaves the prism, refraction occurs at both surfaces, and because shorter wavelengths bend more than longer wavelengths, the colors spread out into a visible spectrum. That is why the object made of glass that disperses white light into a spectrum is called a prism.

Other options don’t produce the same rainbow effect in the same way. A convex lens changes focus and can bend light, but its primary role is to converge light rays, not to separate colors into a spectrum. A concave lens diverges light but doesn’t create a spectrum. A pyramid isn’t designed to cause the controlled dispersion that a prism does, so it doesn’t reliably produce a rainbow from white light.