Lenses

Question 1

what does a converging lens look like (convex)

Answer 1

bulges outwards

Question 2

what does a diverging lens look like (concave)

Answer 2

caves inwards

Question 3

what does a converging lens do

Answer 3

causes rays of light parallel to the axis to converge at the principle focus (brought together)

Question 4

what does a diverging lens do

Answer 4

causes parallel rays of light parallel to the axis to diverge (spread out)

Question 5

what is the focal length

Answer 5

distance from center of lens to the principle focus

Question 6

what is a real image

Answer 6

where the light coming from an object comes together to form an image on the screen

Question 7

what is a virtual image

Answer 7

when rays are diverging so the light from the object appears to be coming from a completely different place

Question 8

what type of image does a magnifying glass show

Answer 8

• a magnifying glass shows a virtual image

- because the point at which the object seems to have been created isnt actually the point in which the light rays meet

Question 9

what type of image does an eye form

Answer 9

• a real image

- because of the image formed on the retina

Question 10

what is the axis of a lens

Answer 10

the line going through the middle of the lens

Question 11

what is the principle focus of a converging lens

Answer 11

where the rays hitting the lens parallel to the axis all meet

Question 12

what is the principle focus of a diverging lens

Answer 12

• the point where rays hitting the lens parallel to the axis appear to all come from
• you can trace them back until they all appear to meet up at a point behind the lense

Question 13

how do light rays act when going through a lens in general

Answer 13

• when they enter the lens, they bend towards the normal due to the change in density (going into a more dense area)
• but when they leave the lens from the other side, they refract away from the normal due to the change in density (going into a less dense area)

Question 14

when are images formed

Answer 14

at points when all the light rays coming form something seem to come together at one point

Question 15

why can a real image be captured on screen

Answer 15

because the light rays actually meet at the place the image seems to be

Question 16

why cant a virtual image be captured on a screen

Answer 16

because the light rays dont actually come together at the point the image seems to be

Question 17

what is the focal length related to and what does it mean

Answer 17

• the power of the lens
• it means that the more powerful the lens
• the more strongly it converges the rays of light
• so the shorter the focal point is from the center of the lense

Question 18

what are the powers in a converging and diverging lense

Answer 18

• the power in a converging lens is positive

- the power in a diverging lens is negative

Question 19

what are the two ways in which you can make a more powerful lens

Answer 19

• by increasing the curvature of the lens or making it with more strongly curved surfaces
• or by using materials that are better at focusing light than others

Question 20

what is the effect of a more powerful lens being able to be created by changing the material in which it ia made from

Answer 20

it means that a more powerful lens can be created that is thinner simply by changing the material it is made from