Florence reflected in the river

Reflection – the return of light, heat or sound.

Our focus here is on the reflection of light and the images that are formed by this reflection.

  • Principle of light reflection (images) – Mirrors, and other reflective surfaces, reflect light in a very predictable manner. The angle at which light approaches the surface is the same as the angle at which light bounces off the surface. This timeless truth regarding light is referred to as the law of reflection.
  • specular reflection – all the light from any single point on an object reflects off a reflecting surface and appears to come together at a single point in space. That point in space is known as the image point of the origin of the light.

What’s the problem?
Two-way glass, reflection and illumination – In police investigations on tv shows, suspects are often seen being interviewed in a room with a two-way mirror.

  • Ask – How can you watch someone in the next room without them seeing you?
  • Imagine – What are some materials that could be used? Is there a way to produce a window that looks like a mirror from the other side? What are some of the properties of light that could be used to make this happen?
  • Plan, Create
  • Improve

To make a museum exhibit to demonstrate the effect of a two-way mirror, the MOAS volunteers started with a piece of glass about the size of a window that had been specially made

The frame holds the glass so you and your friend sit on opposite sides of the window. With normal lighting you see through and you partner sees their reflection. Using the brightness control, as you increase the brightness,

The lights on both sides are connected to a dimmer switch, which control the brightness of the lights by controlling the current through the circuit. Less current, less light.

For the exhibit, as the light gets brighter, the reflection is stronger, so the image of the person on the other side is less visible until it can’t be seen at all.
Engineering ideas

Learn more…

  • Reflection and the Ray Model of Light – The ray nature of light is used to explain how light reflects off of planar and curved surfaces to produce both real and virtual images; the nature of the images produced by plane mirrors, concave mirrors, and convex mirrors is thoroughly illustrated.

Developed by the GE Volunteers in partnership with the Museum of Arts and Sciences (MOAS) – Daytona Beach, FL