Physics colour and lenses

Question 1

Put these in order from longest to shortest wavelength.
Green, Blue, Yellow, Red, Violet

Answer 1

Red as the longest wavelength, violet the shortest.

• red
• orange
• yellow
• green
• blue
• purple
• violet

Question 1

Put these in order from longest to shortest wavelength.
Radio, X-rays, Infrared, UV, Visible light

Answer 1

• radio
• microwave
• infrared
• visible
• ultraviolet
• X-ray
• gamma ray

Question 2

What is white light made up of?

Answer 2

• all of the colours of the spectrum

Question 3

What are the primary colours?

Answer 3

Red, Green, Blue

Question 4

What are the secondary colours?

Answer 4

Yellow, Magenta, Cyan

Question 5

What does mixing two primary colours make?

Answer 5

• a secondary colour

Question 6

What does mixing all the primary colours make?

Answer 6

• white

Question 7

What colour would you get if you mixed green light and blue light?

Answer 7

When green and blue combine you get cyan light.

Question 8

White light shines on a red filter.
What colour(s) does the filter block?

Answer 8

A red filter blocks all colours of light except red.
So a red filter only allows through red light.

Question 9

If magenta light shines through a red filter, what colour light appears behind?

Answer 9

Magenta is made up of red and blue light.
The red filter absorbs the blue light, so once again only red light reaches the other side.

Question 10

If cyan light shines through a red filter, what colour light appears behind?

Answer 10

Cyan is made up of green and blue light.
The red filter absorbs the blue and green light, so no light reaches the other side.

Question 11

What is white light made up of?

Answer 11

White light is made up of the spectrum of colours.

Question 12

What do primary colours do?

Answer 12

Primary colours combine to get secondary colours.

Question 13

What do the filters absorb?

Answer 13

Filters absorb colours other than the filter. A blue filter would only allow blue light through.

Question 14

Can opaque objects be seen through?

Answer 14

Opaque objects cannot be seen through and their colour depends on pigments in the surface materials.

Question 15

If I have a white object and shine red light onto it, what colour would it appear?

Answer 15

The object would appear red, since white light contains all the colours of the spectrum, but the red object only reflects red light

Question 16

If I shine yellow light onto a cyan object, what colour would it appear?

Answer 16

Yellow light is made up of red and green.
A cyan object can only reflect blue or green.
The red is absorbed.
There is no blue light to start with.
So the only colour reflected is green

Question 17

If I shine magenta light on a green object, what colour will it appear?

Answer 17

Magenta light is made up of red and blue.
A green object can only reflect green.
The red and blue are absorbed.
There is no green light to start with.
So no colour is reflected, the object appears black.

Question 18

What does the colour of an object depend on?

Answer 18

Objects appear different colours based on what they reflect.
A red object will reflect red light but absorb other colours.

Question 19

What do transparent objects allow?

Answer 19

Transparent objects allow all the incident light to pass through, none is absorbed.

Question 20

What do translucent objects allow?

Answer 20

Translucent objects let light pass through but it is scattered or refracted. A frosted window would be translucent.

Question 21

What passes through an opaque object?

Answer 21

No light passes through an opaque object.

Question 22

What happens when light passes into a lens?

Answer 22

The light slows down as it enters the lens

Question 23

What does the word converge mean?

Answer 23

Converge means the lines will meet at a point.
This means parallel rays of light will converge to a point when they pass through a convex lens.

Question 23

A picture is 3cm high, when viewed under a magnifying glass it has an image height of 4.5cm. What is the magnification of the lens?

Answer 23

Magnification = (Image Height)/(Object Height)

Magnification = 4.5/3

Magnification = 1.5

Magnification does not have a unit.

Question 24

What does a convex lens cause?

Answer 24

A convex lens causes parallel rays of light to converge to a point called the principal focus or focal point.

Question 25

To work out the magnification produced by a lens what equation can we use?

Answer 25

Magnification = (Image Height)/(Object Height)

Question 26

What does a concave lens cause?

Answer 26

A concave lens causes parallel rays of light to diverge as if they had come from a point called the principal focus.

Question 27

What is the focal point?

Answer 27

The focal point is where parallel rays converge towards or appear to diverge from in the diagram.

Question 28

Look over cognito on how to draw ray diagrams ! and my gcse science

Question 29

How is an image real or virtual?

Answer 29

Real or Virtual, if either line forming the image is dashed the image is virtual. Alternatively images on the same side of the lens as the object will be virtual.

Question 30

How is an image upright or inverted?

Answer 30

Upright or Inverted, if the image points up like the object it is upright.

Question 31

How is an image diminished or magnified?

Answer 31

Magnified or Diminished, if the image is larger than the object (in height) then it is magnified, smaller is diminished.

Question 32

What are some examples of lenses?

Answer 32

Examples include:

Cameras
Your eye
Magnifying glass