Performance Indicator 4.4:
Light
Light comes to us in the form of a wave. An electromagnetic wave to be exact. Electromagnetic waves are grouped according to their wavelengths. Waves with short wavelengths have high energy. Waves with long wavelengths have low energy. Examples of electromagnetic waves in order from short wavelength/high energy to long wavelength/low energy are: Gamma Rays, X-Rays, Ultraviolet Rays, Visible Light (such as Violet, Indigo, Blue, Green, Yellow, Orange, and Red.), Infrared Waves, Microwaves, and Radio Waves.
This light energy can pass through or bounce off matter. When light passes through matter it Refracts, bounces off matter it Reflects. Light, as all waves, when passing from one type of matter to another will change speed and direction. When light bounces off a surface the angle at which the light bounces off equals the angle at which the light hit the surface. In simple term, the incoming and out going angles are equal. The angle of incidence equals the angle of reflection. For you to be able to see an object light must bounce off of that object. For example, when you are in the dark in your room you cannot see anything. But as soon as you turn on the light you can see everything in you room. This is a very simple example. However it goes much deeper. Lets say you are wearing a red shirt. Your red shirt is reflecting red wavelengths of light. This same red shirt is absorbing all other colors of light.
Sound
Sound travels in the form of vibrations through matter. These sound waves travel as a longitudinal wave. These wave disturbances travel away from the source. Sound travels fastest through solids and slowest though gases. Sound cannot travel in a vacuum.
Electricity
Electrical energy can come form many sources. Electricity can come from:
Electricity travels through a path called a circuit. A series circuit has only one path for the electrons to travel while the parallel circuit has more than one path for the electrons to travel.
Magnetism
Magnets have two poles a North and a South. Without contact magnets can attract or repel each other. Magnetic material is attracted to the magnetic field of the magnet. Opposites attract while likes repel. The force of attraction is strongest at the poles.
