Light and the electromagnetic spectrum Study Guide

Reflection occurs when light rays bounce off a surface. The way light reflects depends on the nature of the surface. There are two primary types of reflection: specular reflection and diffuse reflection. Specular reflection happens when light rays reflect off a smooth, polished surface, such as a mirror or still water. In this case, all incident parallel light rays reflect as parallel rays in a single direction, resulting in a clear, sharp reflected image. The angle of incidence equals the angle of reflection for each ray. Conversely, diffuse reflection occurs when light rays strike a rough or uneven surface, like matte paint or a brick wall. The irregularities in the surface cause parallel incident light rays to scatter in various directions. This scattering means no clear image is formed, but it allows objects to be seen from multiple angles, which is why most objects around us are visible. Both types of reflection obey the law of reflection locally for each tiny point on the surface.

The electromagnetic spectrum is a continuous range of all possible electromagnetic waves. These waves are oscillations of electric and magnetic fields that travel through a vacuum at the speed of light, approximately 3.00 × 10^8 m/s. The spectrum is continuous, meaning there are no gaps between different types of waves; instead, they smoothly transition from one to another based on their wavelength and frequency. The primary groupings within the spectrum, from longest wavelength and lowest frequency to shortest wavelength and highest frequency, are radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays. All electromagnetic waves transfer energy from source to absorber.