What is Light What is Light Light is

What is Light?

What is Light? • Light is electromagnetic radiation. o This means it is a combination of electrical energy and magnetic energy. o Light is the only energy we can see.

Photons • Light is made up of tiny particles called photons.

How does light travel? • Light waves travel in straight lines called rays. Laser

• Light travels VERY FAST – around 300, 000 kilometres per second. At this speed it can go around the world 8 times in one second.

Natural Light Source • A natural light source is light that occurs naturally in nature. • Examples 1. 2. 3. 4. Sun Stars Lightening Fireflies

Artificial Light • Artificial light is light that is produced by something that is man made. • Examples: 1. Light bulb 2. Flash light 3. Candles 4. Fire

When light hits an object, it can be absorbed. Absorbed is when light hits an object and is taken in by the object. Black objects absorb almost all of the light that hits them. White objects absorb almost NO light.

Another way light can interact with matter is reflection. In REFLECTION, REFLECTION light bounces off an object. The light changes direction and then continues to move in a straight path.

Surfaces That Reflect Light: Smooth, shiny surfaces reflect almost all the light falling on them. Dull, rough surfaces reflect the least amount of light.

Is the pencil really cut into 2 pieces? NO The water is refracting the light. REFRACTION is the bending of light as it passes from one material to another. When light travels through dense materials, it slows down and bends. Water is denser than air, so light rays refract where water and air meet.

Lenses A lens is a tool that refracts light. CONCAVE convex *inward, curved shape*bulges outward at the center *Refracts light outward *Refracts light toward center. *Light rays spread apart. *Makes objects appear bigger.

What Happens When Light Hits Different Objects? Opaque objects block light from passing through them.

Transparent objects allow light to pass through them.

Translucent objects let light pass through them, but scatter light.

Opaque objects can cause shadows to form. A shadow is a dark space that forms when light is blocked. *A shadow’s size depends on where a light source is. *The closer an object is to a light source, the bigger its shadow. *Light coming from above creates a short shadow. *As the light source gets lower, the shadow gets longer.

Why Can You See Colors? What color is light from the Sun? *You might say white or yellow. In fact it is a mixture of ALL colors! *White light is made of EVERY color of light! To show this, you could look at a prism. A prism is a piece of glass that refracts light into different colors. Prisms refracts each color of light a different amount.

Colors of the Spectrum R O Y GB I V • Red • Orange • Yellow • Green • Blue • Indigo (Dark Blue) 2 • Violet (Purple) 19

This man’s shirt is turquoise, because it’s reflecting turquoise light. Therefore, it’s absorbing all other colors. 4 20

What color of light is reflected? YELLOW 5 21