1. LIGHT
Many properties of light can be understood using a wave model of light.

2. Light Light: a form of energy that can be detected by the human eye.
Visible light: is a light wave that you can see. It is a mixture of all the colours of the rainbow.

3. Radiation of light
Light is transferred by radiation. When you switch on the light in room at night, the whole room becomes illuminated because light is emitted from the bulb and radiates in all directions.

4. Properties of Visible Light...
Light travels in a straight line... (rectilinear propagation)

5. A simple ray diagram of light that is radiated from a candle.

6. The pinhole camera This is a very simple apparatus that
is used to form an upside down
image of a luminous object on a
screen.

7. A ray diagram of the object and the object’s image on the pinhole camera’s screen.

8. Speed of light approximately 300 000 kilometres per second.
Calculate time from the Sun to the Earth if distance is 150 million kilometres.

9. Light travels in waves

10. Visible Light Spectrum
If light waves are passed through a prism, it is refracted into a rainbow of colors
Each color has a different wavelength, longer wavelengths refract less than shorter wavelengths

11. Refraction is the bending or changing direction of a wave as it passes from one material to another.
White light (sunlight) is made up of waves having different wavelengths and frequencies.

12. Except when white light passes through some materials. It can bend
Except when white light passes through some materials. It can bend. Light refracts (Refraction)
Bent Stick

13. The constituent colors of white light are:
Red
Orange
Yellow
Green
Blue
Indigo
Violet
ROY G BIV
**Red has the smallest refraction and violet has the greatest.

14. Light and The Electromagnetic Spectrum
Visible light (the light we see) is only a small portion of the waves around us.
There are invisible waves around us, some are travelling right through us.

15. Frequency, Wavelength and Energy
The longer the wavelength, the lower the frequency
A. a wave passes through an area once in a second.
Frequency = 2 Hertz
B. 4 waves pass through the same area in a second. Frequency = 4 Hertz

16. What wave has the highest frequency?
“B” has the highest frequency
“B” has the shortest wavelength
What wave has the most energy?
“B” has the most energy because it has the highest frequency and it has the shortest wavelength
High frequency waves have shorter wavelengths and produce more energy

17. 4. Visible Light Spectrum
Can be continually detected by our eyes.
(look back at slide 12)