Year 8 Light

Question 1

What are the three secondary colours of light and what are they made of?

Answer 1

Cyan - blue and green, magenta - red and blue, yellow - green and red

Question 2

How do coloured surfaces work?

Answer 2

They reflect light of the colour they are and absorb all the other colours

Question 3

What is reflected if you shine white light onto a red surface?

Answer 3

Red

Question 4

Is this lens convex or concave?
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Answer 4

Concave

Question 5

What is reflected if you shine white light onto a yellow surface?

Answer 5

Red and green

Question 6

What are the colours of the spectrum of light?

Answer 6

Red, Orange, Yellow, Green, Blue, Indigo, Violet

Question 7

What is reflected if you shine green light onto a red surface?

Answer 7

Nothing - you see the object as black

Question 8

How do old 3D images work?

Answer 8

On one eye you wear a red lens and on the other a blue one. The images uses lots of red and blue lines. On the eye with the blue lens you cannot see any of the red on the image, and vice versa for the other eye. This tricks your brain into thinking you are seeing a 3D image, as you are seeing two images

Question 9

What are the three primary colours of light?

Answer 9

Red, green and blue

Question 10

What do you get if you mix all the colours of light?

Answer 10

White

Question 11

What does a diverging lens do?

Answer 11

Spreads light

Question 12

How does refraction work?

Answer 12

When light enters a denser material at an angle the side of the beam of light that hits it first slows down first, as it is hitting more particles, while the other side remains the same speed. This makes it change direction

Question 13

What is reflected if you shine red light onto a yellow surface?

Answer 13

Red

Question 13

Fill in the gaps: When light enters a denser material it bends ________ the normal. When light exits a denser material into a less dense one it bends ________ the normal.

Answer 13

1. Towards

2. Away from

Question 15

Are converging lenses convex or concave?

Answer 15

Convex

Question 16

What is the normal?

Answer 16

An imaginary line at 90º from an object

Question 17

What does a converging lens do?

Answer 17

Focuses light

Question 18

Are diverging lenses convex or concave?

Answer 18

Concave

Question 19

What is wrong with shortsighted people and how can it be fixed?

Answer 19

Their eyes focus the light too late - after the retina. It can be fixed with a convex lens

Question 20

Where should the image in your eye be focussed on?

Answer 20

The retina

Question 21

What is the point where the rays of light come together called?

Answer 21

The focal point

Question 22

What is it called when white light is split up into the spectrum?

Answer 22

Dispersion

Question 23

Who discovered infrared?

Answer 23

Herschel

Question 24

How was infrared discovered?

Answer 24

Herschel measured the temperature of different parts of the spectrum of light and found that red and colours by it were much hotter than blue and colours by it. He then measured just past red and found it to be even hotter

Question 25

Where is infrared on the electromagnetic spectrum?

Answer 25

Just below red, a part of visible light

Question 26

Who discovered ultraviolet?

Answer 26

Ritter

Question 27

How was ultraviolet discovered?

Answer 27

Ritter used silver chloride, a chemical that blackens in sunlight, on different parts of the spectrum. It discoloured very slowly in red light, but much quicker in violet light. He tried just past violet and found it discoloured even quicker.