light

Question 1

how does a concave lens work?

Answer 1

a concave lens bends inwards and causes light to diverge. spread out

Question 2

how does a convex lens work?

Answer 2

a convex lens bulges outwards and causes light to converge. come together

Question 3

what is the principal focus of a convex lens?

Answer 3

the point where all the rays meet.

Question 4

what is the principal focus of a concave lens?

Answer 4

the point where rays hitting the lens parallel to the axis appear to have come from.

Question 5

what is the axis of a lens?

Answer 5

a line passing through the middle. horizontally

Question 6

what is the focal length of a lens?

Answer 6

the distance from the centre of the lens to the principal focus point.

Question 7

what are the 3 rules of refraction for a convex lens?

Answer 7

1. an incident ray parallel to the axis refracts and passes through the principal focus point on the other side.
2. an incident ray passing through the principal focus refracts and travels parallel to the axis.
3. an incident ray passing through the centre of the lens refracts and carries on in the same direction.

Question 8

what are the 3 rules of refraction for a concave lens?

Answer 8

1. an incident ray parallel to the axis refracts and travels in line with the principal focus. it looks like it came from the principal focus
2. an incident ray travelling towards the principle focus refracts and travels parallel to the axis.
3. an incident ray passing through the centre of the lens refracts and carries on in the same direction.

Question 9

what is a ‘real’ image?

Answer 9

an image that can be displayed on a screen. because light converges

Question 10

what is a ‘virtual’ image?

Answer 10

an image that cannot be displayed on a screen and it looks like light comes from behind the lens. because light doesn’t converge

Question 11

how do you properly describe an image? lenses and stuff

Answer 11

1. how big it is.
2. if it’s upright or inverted.
3. if it’s real or virtual.

Question 12

how do you draw a ray diagram for a convex lens?

Answer 12

1. draw the symbol for a convex lens line with outwards arrows and an axis for the lens.
2. draw in the focal points on the axis.
3. draw an object.
4. draw a ray going parallel along the axis to the lens then refracting down through the focal point.
5. draw another ray going from the top of the object through the middle of the lens.
6. the point where the refracted rays meet is the top of the new image.
7. redraw the image flipped.

Question 13

how does distance from the lens affect the image? F 2F etc

Answer 13

an object at 2F produces a real inverted image the same size at 2F.
an object between 2F and F produces a real inverted image bigger beyond 2F.
an object closer than F produces a virtual upright image bigger on the same side.

Question 14

how do you draw a ray diagram for a concave lens?

Answer 14

1. draw the symbol for a concave lens line with inwards arrows and an axis for the lens.
2. draw in the focal points on the axis.
3. draw an object.
4. draw a ray going parallel along the axis to the lens then refracting upwards and draw a dotted line going back to the principal focus.
5. draw another ray going from the top of the object through the middle of the lens.
6. the point where the dotted and regular lines meet is the top of the new image.
7. redraw the new image.

Question 15

what type of image does a concave lens always produce?

Answer 15

a virtual image. the correct way up smaller and on the same side

Question 16

what is the formula for magnification?

Answer 16

magnification = image height ÷ object height

Question 17

what is white light made of?

Answer 17

all the colours of the visible spectrum.

Question 18

what are the primary colours? of light (3)

Answer 18

red.
green.
blue.

Question 19

what is the range in wavelengths of the visible spectrum?

Answer 19

400nm to 700nm.

Question 20

what does opaque mean?

Answer 20

does not transmit light light cannot pass through but can absorb and reflect it.

Question 21

what causes object to appear coloured?

Answer 21

the colour of an object depends on which wavelengths are best reflected. the other wavelengths are absorbed

Question 22

how are not primary colours reflected?

Answer 22

combinations of the primary colours are reflected to make a new colour.

Question 23

what does opaque mean?

Answer 23

does not transmit light light cannot pass through but can absorb and reflect it.

Question 24

what colours do white and black objects reflect?

Answer 24

white reflects all colours.
black reflects no colour.

Question 25

what does transparent mean?

Answer 25

see through.

Question 26

what does translucent mean?

Answer 26

partially see through.

Question 27

what does a colour filter do?

Answer 27

only transmits lets pass through specific colours. wavelengths

Question 28

what happens if you look at an object through a colour of colour filter the object does not reflect?

Answer 28

the object appears black.