Light 2

Question 1

What is a prism?

Answer 1

A triangular piece of glass (or transparent substance) that separates white light as it passes through the prism into a spectrum of colours.

Question 2

What happens as a single ray of light passes trough a prism?

Answer 2

As the ray of light enters the prism, the light slows down and refracts towards the normal.​ Then as the ray of light leaves the prism, the light speeds up and refracts away from the normal.​

The white light is split into different colours because each colour refracts by different amounts. ​

Question 3

What causes a rainbow?

Answer 3

A rainbow is created by sunlight being refracted through water droplets (each droplet acts as a little prism).

Question 4

List the colours of the spectrum

Answer 4

ROYGBIV

Red
Orange
Yellow
Green
Blue
Indigo
Violet

Question 5

Which colour of the spectrum is refracted the most and which is refracted the least?

Answer 5

Red is refracted the least, and violet the most.

Question 6

Name the three primary colours of light

Answer 6

Red, blue and green

Question 7

What are the three secondary colours?

Answer 7

Magenta, cyan and yellow

Question 8

Which primary colours are added together to produce cyan?

Answer 8

Colour mixing (equal brightness of light from each) blue and green.​

Question 9

Which primary colours are added together to produce magenta?

Answer 9

Colour mixing (equal brightness of light from each) blue and red.

Question 10

Which primary colours are added together to produce yellow?

Answer 10

Colour mixing (equal brightness of light from each) red and green.

Question 11

How do we get all the other colours we can see?

Answer 11

Mixing different colours of light together in different amounts can produce any colour you can think of.

Question 12

What is a filter?

Answer 12

Filters only allow certain colours (specific wavelengths) of light to be transmitted (passed through)

Question 13

What will a primary coloured filter transmit?

Answer 13

Coloured filters only let through (“transmit”) their own colour. ​

All the other colours are taken in (“absorbed”) by the filter – so they don’t get through.

Question 14

What colour of light would a green filter let through?

Answer 14

A green filter only lets through green light, all the other colours which make up white light are absorbed.​

Question 15

What happens if we put two primary coloured filters put together, for example blue then red?

Answer 15

A blue filter only lets through blue light. ​

A red filter only lets red light through but there is no red light to let through so no light is seen.​

Using two primary coloured filters stops all transmission of light!

Question 16

What happens when the filter used is not a primary colour?

Answer 16

When the filter used is not a primary colour, the filter will allow more than one colour through.
For example cyan is made of blue and green, so will transmit blue and green.

Question 17

What is the use of filters in everyday life?

Answer 17

Theatre lights, Traffic lights, car lights, indicators, brake lights

Question 18

Explain how do we see a red car as red?

Answer 18

When light shines on coloured objects say a red car the blue and green light is absorbed.

Only the red light is reflected (bounces off the object) which goes into your eye and you see the car as red ​

Question 19

Why do we see a banana as yellow?

Answer 19

Because yellow is made from the primary colours red and green, yellow things reflect both red and green colours of light. They absorb blue light.​

Question 20

Is white a colour?

Answer 20

White is not a true physical colour white things reflect all of the colours of light​…..
So white is what we see when all wavelengths of light are reflected off an object.

Question 21

Is black a colour?

Answer 21

Black is not a true physical colour. Black things do not reflect any light. All the colours of light are absorbed.​ So black is what our eyes see in a space that reflects very little light at all.

Question 22

Name two different forms of invisible radiation and where they are used in medicine.

Answer 22

X-rays are used to detect broken bones.
Infrared is used repair damaged muscle tissue, Ultraviolet is used to treat skin disorders such as acne.

Question 23

Why can too much exposure to UV radiation be harmful and how can you protect yourself from the suns damaging effects?

Answer 23

Ultraviolet (UV) radiation is emitted by the sun and artificial sources, such as tanning beds and can be dangerous to humans​.

Too much UV can cause skin cancer​. However this can be prevented with sun screen, protective clothing such as sun hats and sunglasses and staying in the shade when it is too warm.