lenses and light (topic 6)

Question 1

state the name of the point labelled F

Answer 1

principal focus or focal point

Question 2

Answer 2

Question 3

state the name of this type of lens

Answer 3

convex lens or converging lens

Question 4

describe the image formed by the converging lens (3)

Answer 4

• real image
• diminished, smaller
• inverted, upside down

Question 5

the object is brought closer to the lens, draw two rays of light to show the location of the image formed

Answer 5

Question 6

describe the image formed when the object is closer than the focal point

Answer 6

• virtual image
• magnified
• upright

Question 7

Answer 7

all light rays refract to pass through the focal point after the lens

Question 8

when is a virtual image formed by a convex lens

Answer 8

when the object is less than one focal length from the lens

Question 9

Answer 9

Question 10

which is a concave lens

Answer 10

B

Question 11

Answer 11

Question 12

describe the image formed (3)

Answer 12

• virtual
• upright
• diminished

Question 13

the image formed by a magnifying glass is virtual or real

Answer 13

virtual

Question 14

describe the image formed (3)

Answer 14

• virtual
• upright
• magnified

Question 15

the student wants to make the image larger, describe how they should vary the distance between the lens and the object (1)

Answer 15

• increase the distance between the object and lens slightly
• or keep lens stationary and move the object closer to the principal focus of the lens

Question 16

Answer 16

Question 17

they shine white light through a red filter, explain what the student would observe on the screen (3)

Answer 17

• student observes a red spot of light on the screen
• the red filter would absorb all wavelengths of light except red
• red light is transmitted by the filter

Question 18

a green filter is then placed behind the red filter, describe what the student would observe on the screen, and explain why (2)

Answer 18

• screen would appear black
• all wavelengths of visible light absorbed by combination of red and green filters

Question 19

Answer 19

Question 20

each student observes the object and recalls what they saw.:
- student A states the object at the centre looked red
- student B states the object at the centre looked black
- student C states the object at the centre looked blue, the coloured object has a magenta colour, explain which colours of light make up the colour magenta, use the student’s observations in your answer (3)

Answer 20

• magenta contains red and blue light
• (student A saw the object as red because) the red filter transmitted red light from the object
• (student B saw the object as black because) the green filter absorbed the light from the object
• (student C saw the object as blue because) the blue filter transmitted the blue light from the object

Question 20

each student places another filter behind their first filter, this new filter is a different colour, describe and explain what each student would observe (2)

Answer 20

• all students would now see black
• any light that is transmitted by the first filter is absorbed by the second filter

Question 21

in a school play an actor is wearing green trousers, they are illuminated with red light, explain why the green trousers no longer appear green (2)

Answer 21

• red light is absorbed by the green trousers
• trousers appear black (when illuminated in red light) because no light is reflected

Question 22

another actor is wearing yellow clothing, yellow is comprised of both red and green wavelengths of light, explain how the yellow clothing will appear to the audience when illuminated with green light (1)

Answer 22

the clothing will reflect the green light to appear green