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# Mirrors Reflect Light

This lesson aligns with NGSS PS4.B

Introduction
Have you ever taken a moment to examine your reflection in a metal spoon? The polished metal surface of the spoon acts like a mirror, but not like the mirror you have hanging in your bathroom. When you look at your reflection on one side of the spoon, your face appears upside down. But if you flip the spoon and look at the other side, your face magically appears right side up. Why does this happen? How light reflects off different surfaces has everything to do with the shape of the reflecting surface. Consequently, the image you see in your bathroom mirror can vary from what you see in a spoon. In this article, we will learn about how rays show the path of light waves, and how different mirrors reflect light.

Rays Show the Path of Light Waves
To understand the process of image formation in mirrors, we must first learn how to use rays to trace the path of light waves.

Light is an electromagnetic phenomenon. It propagates outward in all directions from its source. If we were to trace the trajectory of a single light wave as it travels away from a light source, we would observe that it follows a linear path. This property of light waves moving in straight lines enables us to represent their path and direction using an arrow known as a ray. In the mentioned figure, we can see several rays originating from a light bulb.

Rays are also valuable for illustrating the trajectories of light waves after they undergo reflection or refraction. Consequently, ray diagrams are used to show alterations in the path of light as it is reflected by mirrors or refracted by lenses.

Plane Mirrors
Most mirrors, such as the one commonly found in bathrooms, are classified as plane mirrors. A plane mirror possesses a flat surface. When you look into a plane mirror, you perceive your reflection as upright and of the same size as your actual self. However, images in plane mirrors exhibit a left-to-right reversal, as demonstrated in Figure.

When you see yourself in a plane mirror, your reflected image seems to be located at the same distance behind the mirror as you stand in front of it. But why does this illusion of an image behind the mirror occur?

The phenomenon can be explained by the fact that mirrors are solid and do not permit the passage of light through them. However, when light reflects off the mirror's surface, your brain interprets this reflected light as though it were traveling in a straight line from a point behind the mirror. This optical trick results in the creation of a virtual image, which is an image through which light does not travel. The image formed by a plane mirror is virtual.

• Light bounces off of the object and strikes the mirror, where it is reflected again. A portion of this reflected light enters your eyes.
• The image of the object seems to be behind the mirror because your brain assumes that the light rays that enter your eyes travel in a straight line from an object to your eyes.

Summary
• Light propagates outward in all directions from its source. Light wave travels away from a light source, and it follows a linear path.
• A plane mirror has a flat surface. When you look into a plane mirror, you perceive your reflection as upright and of the same size as your actual self.
• The image formed by a plane mirror is virtual.
• The image of the object seems to be located behind the mirror because your brain assumes that the light rays that enter your eyes travel in a straight line from an object to your eyes.

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