Reflection

Mahi Tuatahi

Blooket

Radiation

Copy this paragraph into your book, using these missing words: electromagnetic, sun, energy, groups, movement.

Radiation is the ……………………… of energy from a source. Examples of radiation could include water waves, sound waves and ………………………………… waves. Electromagnetic waves are produced by the ……………… These waves travel at high speed and unlike sound and water waves do not need matter to transfer the ………………………… The waves can therefore travel in space across a vacuum. Electromagnetic waves can be put into different ……………………………, depending on the size and properties of the waves.

Te Whāinga Ako

1. I can describe regular reflection and give some examples of its use.

Pātai Tahi: Why do some objects reflect light?

Whakatika Tahi

Because they do not absorb much light, instead they reflect almost all of it away!

Pātai Rua: Why do some reflections form images?

Whakatika Rua

• Smooth surfaces reflect light regularly
• This means the light rays are reflected in the same order, forming an image

Sketch this diagram accurately into your book. Ensure that you add the labels.

Looking at the diagram you sketched, what can you say about the angle of incidence and the angle of reflection?

The Law of Reflection

The angle of reflection is equal to the angle of incidence

Secret Spy

Victor is a spy on a mission to find out gossip about Charles. Unfortunately for Charles, his dance moves are pretty embarassing. Victor wants to place a mirror in this hallway so that he can catch Charles in the act. Where should he place the mirror?

1. Sketch this diagram into your book.
2. Add a mirror in the correct position and orientation to allow Victor to spy on Charles’ dance moves.
3. Draw a light ray coming from Charles and going to Victor.
   • Label the incident ray
   • Label the reflected ray

Uses of Reflection

• A fibre optic cable works by reflection.
• Light rays travel down the cable and reflect off the inside walls of the cable even when it is bent.
• This is called total internal reflection

Surgery

• Endoscopes use optical fibres.
• A doctor can insert a bundle of optical fibres into the body to see the inside of the body clearly – and help them diagnose diseases or see what they are doing during keyhole surgery.

The internet uses fibre optic cables across the bottom of the ocean to connect countries and continents.