1. Light Filters

2. What is a Light Filter? A light filter is a transparent material, that contains a pigment, that allows only specific colours of light to pass through it. A light filter is a transparent material, that contains a pigment, that allows only specific colours of light to pass through it. For example, a red light filter allows red light to pass through it while absorbing all other colours of light. For example, a red light filter allows red light to pass through it while absorbing all other colours of light. A pigment is a colouring agent that absorbs certain colours of light and reflects other colours of light. A pigment is a colouring agent that absorbs certain colours of light and reflects other colours of light.

3. Light Filters in Action The filter on top is red so it blocks every colour except for red – which passes through so we see red light. The filter on top is red so it blocks every colour except for red – which passes through so we see red light. The bottom filter is a blue filter so only blue light gets through. The bottom filter is a blue filter so only blue light gets through.

4. Light Filters in Action http://www.youtube.com/watch?v=zvfdOiBDgXA http://www.youtube.com/watch?v=zvfdOiBDgXA

5. Wait a Minute!!!... The previous video showed red light passing through a red filter…that seems OK… The previous video showed red light passing through a red filter…that seems OK… Then it showed the red light getting blocked by the blue filter…that seems OK too… Then it showed the red light getting blocked by the blue filter…that seems OK too… BUT, what happens when the red light is still able to pass through the yellow filter? Shouldn’t the yellow filter block the red light since they are two different colours? How is that possible? BUT, what happens when the red light is still able to pass through the yellow filter? Shouldn’t the yellow filter block the red light since they are two different colours? How is that possible? You have to remember that yellow light is made up of both red and green light mixed together. Each filter only lets its own colour light through and yellow treats red and green as its own light because they are the components of yellow light. You have to remember that yellow light is made up of both red and green light mixed together. Each filter only lets its own colour light through and yellow treats red and green as its own light because they are the components of yellow light.

6. Predict the Following!

7. THE END