Activity 4

The life cycle of the photon involves the life (creation) and death (disappearance) of the photon - a particle of light. The description of the photon can be applied to the entire electromagnetic spectrum from radio waves to gamma rays. Note that sound - vibration of air molecules - is not a photon.

The photon behaves as both a particle and a wave. The particle behavior is hard to describe without laboratory equipment, but you can see wave behavior. Hold your thumb and forefinger close together and look at a light source. As you bring your thumb and finger together you will see a series of dark lines - at least one dark line - between them. This is wave behavior.

If you have a candle on a table, you will see that light is given off in all directions. If you hold the Fresnel lens a focal length away you can produce a beam of light (your own light house).

Without a lens the amount of light you receive decrease with distance. Make a circle with your thumb and forefinger. Look at a light bulb without lens or reflection. Note that the light appears dimmer as you move back.

Therefore the amount of light received per unit area decreases rapidly with distance from the source. We receive less light per unit area of detection, the further we are from the candle.

Think about Superman. How could he visualize a scene with x-rays? The comics only show rays of x-rays from his eyes and the rays illuminating a person or an object. What would he need to "see" the x-rays?

To read more about photons, go to the Reading on The Life Cycle of the Photon