1. 4.1 What is Light?

2. LEARNING GOAL Today we will learn that light is energy, and it travels like a wave. SUCCESS CRITERIA We will be successful if we can Explain and identify the wavelength in a wave. Explain what an electromagnetic spectrum is.

3. Light as a Wave Light is a form of energy. Visible light is only a tiny fraction of the energy that surrounds us every day. We are also surrounded by invisible light-like waves, which together with visible light are called electromagnetic radiation.

4. Light as a Wave Waves carry energy Electromagnetic waves carry electrical and magnetic energy Radiation is a process in which energy travels through space. Light is a form of radiation. Other forms of radiation include microwaves, x-rays and radio waves

5. Wavelength - the distance between peaks on a wave. - determines how it can be used and whether you can see it.

6. Electromagnetic Spectrum The wavelengths and uses of types of electromagnetic radiation can be represented as a spectrum.(see p282-283 Figure 4.5)

7. Electromagnetic Spectrum The only waves of the electromagnetic spectrum that you can see are those of visible light.

8. The Visible Spectrum - Red light is at one end, violet at the other, and all the other colours in between. - Red light has LONGER wavelengths while violet has SHORTER wavelengths

9. White light really isn’t white? A prism separates white light into the colours of the rainbow. ROY G BV = red, orange, yellow, green, blue, and violet

10. Classwork -Textbook p.283 “Learning Check” #1-3 -Worksheet: “Light” Homework: Can you please bring empty paper towel rolls for an experiment?

11. What Is White Light Made Of? - Lab Purpose To observe the components of white light Procedure 1. Set the prism upright on the desk so that the rectangular sides are vertical. 2.Place the ray box about 20 cm away from the prism so that the ray shines on the prism. 3.Slowly rotate the prism. Observe the direction of light that emerges from the prism. 4.Hold a piece of white paper in the path of the light emerging from the prism about 50 cm away from the prism. Observe. 5.If you do not see anything interesting, try rotating the prism again.