Difference Between Reflection and Refraction

Reflection vs Refraction

The phenomenon of a light beam rebounding after hitting a surface is called reflection. To put it simply, the mirror images are what are called reflection generally. The light beam that hits the surface is called incident ray. The light beam that leaves the surface is called the reflected ray.
There’s another phenomenon called refraction. Here, the light changes direction, or ‘bends’ as it passes through the boundary between these two media. The images that are witnessed through the glass/see-through objects are a result of refraction.

The angle of incidence and angle of reflection are the same in the case of reflection. For example, when a ray of light strikes a horizontal surface at a 45 degree angle (angle of incidence), it always rebounds at the same 45 degree angle (angle of reflection). These angles are the same even when multiple rays hit the surface and bounce back. For example, a flat mirror produces an image that is upright, and of the same size as the object that is being reflects. The length between the image and object from the mirror also remains the same. This type of reflection is called specular reflection. While most of the objects reflect light in all directions in a microscopic level, the irregularities on the object’s surface will determine the specific rate of reflection. When the light passes through a rough surface, the reflection also happens in different directions. This is called diffuse reflection.

However in the case of refraction, these angles are not the same. Different media participate in refraction, thus making this angle unequal. In reflection, the incident and reflected rays pass through the same medium. Reflection is found in mirrors while lenses use refraction.

During refraction rays of light pass through different media such as a plastic object, a diamond or a glass. During this travel, the light changes its speed and wavelength. However, the frequency of light will be constant.
Let’s visualize a light beam passing through air till it hits a water body. The ray of light arrives at a particular angle to the water surface. As it travels through air to water, the speed of light actually reduces. The part that hits the water first slows down first thus prompting the light to change its direction to an angle that is steeper.

Summary:
1. The phenomenon of a light beam rebounding after hitting a surface is called reflection while the bouncing back of light from its normal path is termed refraction.
2. The angle of incidence and angle of reflection are the same in the case of reflection. These angles are not the same in refraction.
3. Reflection is found in mirrors while lenses use refraction.
4. In reflection, the light returns to the same medium while in refraction, the light travels from one medium to another medium.

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