P14: Light

Question 1

How do lenses form images?

Answer 1

By refracting light

Question 2

What happens in convex lenses?

Answer 2

Parallel rays of light are brought to a focus at the principle focus.

Question 3

What is the focal length?

Answer 3

The distance from the lens to the principle focus

Question 4

What kind of image is produced by a convex lens?

Answer 4

Real or virtual

Question 5

What kind of image is produced by a concave lens?

Answer 5

Always virtual

Question 6

What is specular reflection?

Answer 6

Reflection from a smooth surface in a single direction

Question 7

What is diffuse reflection?

Answer 7

Reflection from a rough surface, causing scattering

Question 8

How do colour filters work?

Answer 8

By absorbing certain wavelengths (and colour) and transmitting other wavelengths (and colour)

Question 9

When is an object white?

Answer 9

When all wavelengths are reflected equally

Question 10

When is an object black?

Answer 10

When all wavelengths are absorbed equally

Question 11

Which colour has the longest wavelength?

Answer 11

Red

Question 12

Which colour has the shortest wavelength?

Answer 12

Violet

Question 13

What does the colour an object appear to be depend on?

Answer 13

The wavelength of light hitting it and the property of the object

Question 14

What are opaque objects?

Answer 14

Those that don’t transmit any light

Question 15

What 2 colours should be reflected to form yellow?

Answer 15

Red and green

Question 16

What are transparent objects?

Answer 16

Those that transmit most light, with a small amount being absorbed

Question 17

What is another name for a convex lens?

Answer 17

Converging lens

Question 18

What does a converging lens do?

Answer 18

It refracts parallel rays of light inwards to a single point (principle focus)

Question 19

What does it mean if the focal length is short?

Answer 19

The lens is more powerful as it refracts light more strongly

Question 20

How would you make a lens more powerful?

Answer 20

Use a different material or make the lens more curved

Question 21

What is the difference between a real image and an imaginary image?

Answer 21

Real image is formed when rays cross but virtual image is where virtual rays cross. Virtual image is where rays seem to come from