GCSE Level Optics Questions

GCSE level optics questions

Q1.The diagram shows a converging lens of focal length 4 cm being used as a magnifying glass. An object 1.6 cm tall is placed 2.4 cm from the lens.

(a) On the diagram, use a ruler to construct accurately the position and size of the image. You should show how you construct your ray diagram and how light appears to come from the image to the eye.

(4 marks)(b) The image is virtual. What is a virtual image?

(1 mark)(c) Calculate the magnification produced by the lens. Show clearly how you work out your answer.

(2 marks)(Total 7 marks)

Q1.The diagram shows a converging lens of focal length 4 cm being used as a magnifying glass. An object 1.6 cm tall is placed 2.4 cm from the lens.

(a) On the diagram, use a ruler to construct accurately the position and size of the image. You should show how you construct your ray diagram and how light appears to come from the image to the eye.Ray from object point through pole of the lens (centre of it!) Ray parallel to the principal axis going through the focal point Extension lines (dashed lines) for both rays meeting at a point Image (dashed lines)

(4 marks)(b) The image is virtual. What is a virtual image?A virtual image is an image formed by the eye/brain of the observer when the brain assumes that diverging rays entering the eye must have travelled in straight lines from a source.A virtual image is not real, so it cannot be picked up on a screen - the rays do not cross at the point in is formed at. Instead rays have to be traced back in a straight line to that point.

(1 mark)(c) Calculate the magnification produced by the lens. Show clearly how you work out your answer.Magnification = size of image/size of object (see diagram) = 17.5/7 = 2.5 (OR Magnification = image distance/object distance = u/v = 30/12 = 2.5) (2 marks) (Total 7 marks)Q2.

(a) The diagram shows two parallel rays of light, a lens and its axis.(i) Complete the diagram to show what happens to the rays.

(2 marks)(ii) Name the point where the rays come together.

(1 mark)(iii) What word can be used to describe this type of lens?

(1 mark)(b) The diagram shows two parallel rays of light, a lens and its axis.

(i) Which point A, B, C, D or E shows the focal point for this diagram?(1 mark)

(ii) Explain your answer to part (b)(i).(1 mark)

(iii) What word can be used to describe this type of lens?(1 mark)

(c) Complete the following three sentences by choosing the correct words from each bracketed section.In a camera a converging lens is used to produce an image on a (film/lens/screen)The image is (larger than/smaller than/the same size as) the object.Compared to the distance of the image from the lens, the object is (further away from/nearer to/the same distance from) the lens.

(3 marks)(d) Explain the difference between a real image and a virtual image.


Q2.

(a) The diagram shows two parallel rays of light, a lens and its axis.(i) Complete the diagram to show what happens to the rays.If diagram brings the rays to a point on the axis award 1 mark.If the diagram shows refraction at each boundary award 2 marks.

(2 marks)(ii) Name the point where the rays come together.The principal focus OR focal point.

(1 mark)(iii) What word can be used to describe this type of lens?Convex lens or converging lens.

(1 mark)(b) The diagram shows two parallel rays of light, a lens and its axis.

(i) Which point A, B, C, D or E shows the focal point for this diagram?A

(1 mark)(ii) Explain your answer to part (b)(i).The focal point must be A as this is a diverging (or concave) lens. The rays are seen to diverge from the virtual focus.

(1 mark)(iii) What word can be used to describe this type of lens?Convex lens or diverging lens.

(1 mark)(c) Complete the following three sentences by choosing the correct words from each bracketed section.

In a camera a converging lens is used to produce an image on a (film/lens/screen) The image is (larger than/smaller than/the same size as) the object. Compared to the distance of the image from the lens, the object is (further away from/nearer to/the same distance from) the lens.

(3 marks)(d) Explain the difference between a real image and a virtual image.A real image of a point on an object is formed where rays of light converge at a point. If a screen is placed at that point the image will appear on the screen. A virtual image is formed only by the eye of the beholder. The rays from which the image is formed are diverging, they never meet at a point, therefore they cannot form an image that is picked up on a screen. The brain/eye of the beholder traces back the light rays entering the ye and perceives an image at the point they trace back to. (Max 3)


Q3.The ray diagram shows the position and size of the image, I, of an object, O, formed by a lens, L.

(a) What type of lens is shown in the ray diagram?(1 mark)

(b) Name the point labelled P.(1 mark)

(c) The ray diagram has been drawn to scale. Calculate the magnification of the object by the lens. Show clearly how you work out your answer.

(2 mark)(d) How can you tell from this ray diagram that the image is a real image?

(1 mark)(Total 5 marks)

Q3.The ray diagram shows the position and size of the image, I, of an object, O, formed by a lens, L.

(a) What type of lens is shown in the ray diagram?Convex OR converging lens.

(1 mark)(b) Name the point labelled P.Focal point or principal focus.

(1 mark)(c) The ray diagram has been drawn to scale. Calculate the magnification of the object by the lens. Show clearly how you work out your answer.Magnification = height of image/height of object = 6 mm/4 mm = 1.5

(2 mark)(d) How can you tell from this ray diagram that the image is a real image?The rays meet at a point - therefore a real image is formed at that point.


Q4.

(a) The diagram shows a motorist looking into her driving mirror.(i) Mark on the diagram: the letter 'I' to show the incident ray and the letter 'r' to show the angle of reflection.

(2 marks)(ii) Name the dashed line shown in the diagram.

(1 mark)(b) List A gives the names of two types of mirror. List B shows how three types of mirror are represented in diagrams. Draw a line from each type of mirror in list A to the correct mirror in list B.


Q4.

(a) The diagram shows a motorist looking into her driving mirror.(i) Mark on the diagram: the letter 'I' to show the incident ray and the letter 'r' to show the angle of reflection.See diagram

(2 marks)(ii) Name the dashed line shown in the diagram.The normal

(1 mark)(b) List A gives the names of two types of mirror. List B shows how three types of mirror are represented in diagrams. Draw a line from each type of mirror in list A to the correct mirror in list B.


Q5.

The diagram shows the image IC formed by a lens, of an object OB a long way from it. The points F mark the focal points of the lens.(a) Describe, either by writing below or drawing on the diagram, how the nature, size and position of the image changes:(i) when the object OB is moved towards the focal point F.(ii) when the object OB is moved past F to a point nearer the lens than the focal point.

(6 marks)(b) Explain how a converging lens in a camera is used to produce sharp images on the film when the object is a long distance away from the camera, and when it is close to the camera.


Q5.

The diagram shows the image IC formed by a lens, of an object OB a long way from it. The points F mark the focal points of the lens.(a) Describe, either by writing below or drawing on the diagram, how the nature, size and position of the image changes:(i) when the object OB is moved towards the focal point F.The size of the image increases and its distance from the lens also increases. The nature of the image does not change - it remains real.(ii) when the object OB is moved past F to a point nearer the lens than the focal point.The nature of the image changes to being virtual. As it nears the lens its size increases and the image is formed further from the lens (but on the same side of the lens as the object).

(6 marks)(b) Explain how a converging lens in a camera is used to produce sharp images on the film when the object is a long distance away from the camera, and when it is close to the camera.When the object is very distant the rays from a point image enter the camera lens travelling virtually parallel to each other. That means that the distance between the lens and the film is equal to the foacl length of the lens.As the object is moved nearer to the lens the image distance has to increase. The lens is therefore moved away from the back of the camera. This is achieved by a 'zoom' facility on the camera which makes the lens move out towards the object. (3 max)


Q6.

Lenses are used in many optical devices. Complete the table above about the images formed by some optical devices.

(Total 6 marks)Q6.

Lenses are used in many optical devices. Complete the table above about the images formed by some optical devices.

(Total 6 marks)Q7.(a) The diagram shows how parallel rays of light pass through a convex lens.

(i) Mark the position of the focus.(1 mark)

(ii) Is this a converging lens, a diverging lens, both or neither?(1 mark)

(b) The diagram shows how parallel rays of light pass through a concave lens.

(i) Mark the position of the focus.(1 mark)

(ii) Is this a converging lens, a diverging lens, both or neither?(1 mark)

(c) Complete these sentences by choosing the correct word or phrase from the brackets.In a camera, a (converging/diverging/parallel) lens is used to produce an image of an object on a(film/lens/screen). The image is (larger than/smaller than/the same size as) the object. The image is(nearer

to/further from/the same distance from) the lens, compared to the distance of the object from the lens.

(4 marks)(d) In a cinema projector, a convex lens is used to produce a magnified, real image.

(i) What does magnified mean?(1 mark)

(ii) What is a real image?(1 mark)

(e) You are in a dark room. You have a box containing some lenses. Only one of them is a converging lens. Describe how, by just feeling the lenses, you can pick out the converging lens.


Q7.(a) The diagram shows how parallel rays of light pass through a convex lens.

(i) Mark the position of the focus.See the diagram

(1 mark)(ii) Is this a converging lens, a diverging lens, both or neither?It is a converging lens (because it makes the rays converge - come together - at a point).

(1 mark)(b) The diagram shows how parallel rays of light pass through a concave lens.

(i) Mark the position of the focus.See the diagram

(1 mark)(ii) Is this a converging lens, a diverging lens, both or neither?It is a diverging lens (because it makes the rays diverge - spread out - from a point).

(1 mark)(c) Complete these sentences by choosing the correct word or phrase from the brackets.In a camera, a (converging /diverging/parallel) lens is used to produce an image of an object on a (film /lens/screen). The image is (larger than/smaller than /the same size as) the object. The image is(nearer to /further from/the same distance from) the lens, compared to the distance of the object from the lens.

(4 marks)(d) In a cinema projector, a convex lens is used to produce a magnified, real image.

(i) What does magnified mean?Magnified means that the image is larger than the object. Magnification is the ratio of the image size to the object size - when this > 1 the image is magnified, if the ratio is <1 the image is diminished.

(1 mark)(ii) What is a real image?A real image is formed when rays from a point on an object converge at a point to form an image. Such an image can be formed on a screen if it is placed at that position.

(1 mark)(e) You are in a dark room. You have a box containing some lenses. Only one of them is a converging lens. Describe how, by just feeling the lenses, you can pick out the converging lens.A converging lens is convex shaped, that means it is thicker in the middle than at the edges. Therefore by feeling the shapes you would look for the one that bulged out in the middle. The concave lenses in the box would be thicker around the edge than in the middle, any lenses that felt like that would therefore be rejected.There are two marks for this part of the question - that is often the case in 'compare and contrast' questions. Therefore even though you aren't asked to describe the lenses you would reject when you handled them, you need to describe their shape too!


Q8.The diagram shows an object located vertically on the principal axis of a diverging lens. A student looks through the lens and can see an image of the object.

(a) Using a pencil and ruler to draw construction lines on the diagram, show how light from the object enters the student's eye and the size and position of the image.

(3 marks)(b) Describe the nature of the image by comparing it to the object.

(2 marks)(Total 5 marks

Q8.The diagram shows an object located vertically on the principal axis of a diverging lens. A student looks through the lens and can see an image of the object.

(a) Using a pencil and ruler to draw construction lines on the diagram, show how light from the object enters the student's eye and the size and position of the image.See the diagram:

One ray from the object point should go undiverted through the pole of the lens into the eye

One ray should travel parallel to the principal axis up to the lens line. It should then emerge from the lens as if it has come from the virtual focus - this should be shown with a dashed line.

The image arrow should be a dashed arrow pointing to the point where the ray and construction line cross.

(3 marks)(b) Describe the nature of the image by comparing it to the object.The image is samller than the object (diminished in size) , it is closer to the lens than the object is (image distance < object distance) ,It is also virtual whereas the object is real but the two above is what the examiner required.


Q9. A student investigated how the nature of the image depends on the position of the object in front of a large converging lens. The diagram shows one position for the object.(a) Use a ruler to complete a ray diagram to show how the image of the object is formed.

(4 marks)(b) Describe the nature of this image relative to the object.

(2 marks)(Total 6 marks

Q9. A student investigated how the nature of the image depends on the position of the object in front of a large converging lens. The diagram shows one position for the object.(a) Use a ruler to complete a ray diagram to show how the image of the object is formed.

Award marks as follows:

Ray through pole of lens is undiverted. Ray parallel to the principal axis passes through the principal

focus after refraction by the lens. Image point should be joined by a perpendicular line to the

principal axis with an arrow head on the top of it.

Rays should have an arrow on them - no arrow means it is not a ray. Therefore lack of arrow heads on rays - deduct 1 mark.No ruler used - deduct 1 mark

(4 marks)(b) Describe the nature of this image relative to the object.It is inverted, magnified and real (3 max)


Q10.

A student investigates how the magnification of an object changes at different distances from a converging lens. The diagram shows an object at distance d from a converging lens.

(a)(i) The height of the object and the height of its image are drawn to scale. Calculate the magnification produced by the lens shown in the diagram. Show clearly how you work out your answer.

(2 marks)(ii) The points F are at equal distances on either side of the centre of the lens. State the name of these points.

(1 mark)(iii) Explain how you can tell, from the diagram, that the image is virtual.

(1 mark)(b) The student now uses a different converging lens. She places the object between the lens and point F on the left. The table shows the set of results that she gets for the distance d and for the magnification produced.

Distance d /cm Magnification

5 1.2

10 1.5

15 2.0

20 3.0

25 6.0Herfriend looks at the table and observes that when the distance doubles from 10 cm to 20 cm, the magnification doubles from 1.5 to 3.0. Her friend's conclusion is that:"The magnifi cation is directly proportional to the distance of the object from the lens." Her friend's observation is correct but her friend's conclusion is not correct.(i) Explain, with an example, why her friend's conclusion is not correct.

(2 marks)(ii) Write a correct conclusion.

(1 mark)(iii) The maximum range of measurements for d is from the centre of the lens to F on the left. The student cannot make a correct conclusion outside this range. Explain why.


Q11.The diagram shows a lens, the position of an object and the position of the image of the object.

(a) What type of lens is shown?(1 mark)

(b) What is the name of the points, F, shown each side of the lens?(1 mark)

(c)(i) The image is real and can be put on a screen. How can you tell from the diagram that the image is real?

(1 mark)(ii) Draw a ring around a word in the box below which best describes the image produced by the lens.

(1 mark)

(d) A student investigates the relationship between the distance from the object to the lens and the magnification produced by the lens. The student's results are given in the table. The student did not repeat any measurements.

Distance/mm Height of object/mm Height of image/mm Magnification

produced

40 20 58 2.9

50 20 30 1.5

60 20 20 1.0

70 20 14 0.7

80 20 12 0.6

90 20 10 0.5The student plots the points for a graph of magnification produced against distance.

(i) Draw a line of best fit for these points.(1 mark)

(ii) Complete the following sentence by drawing a ring around the correct word in the box. "A line graph has been drawn because both variables are described as being ...."

(1 mark)(iii) Describe the relationship between magnification produced and distance.


Q10.A student investigates how the magnification of an object changes at different distances from a converging lens. The diagram shows an object at distance d from a converging lens.

(a)(i) The height of the object and the height of its image are drawn to scale. Calculate the magnification produced by the lens shown in the diagram. Show clearly how you work out your answer.Magnification = image height/object height = 18 mm/ 6 mm = 3.0 Any unit will cause one mark to be deducted - a ratio has no unit!

(2 marks)(ii) The points F are at equal distances on either side of the centre of the lens. State the name of these points.Focal points or principal foci (plural of focus)

(1 mark)(iii) Explain how you can tell, from the diagram, that the image is virtual.

The image is formed at the intersection of dashed construction lines as there is no cross point for the rays.The rays diverge after refraction by the lens therefore they will never meet at a point and form a real image. The eye (and brain) of the beholder therefore traces back the diverging rays to a point that is the virtual focus for the diverging rays. This is shown in the diagram by dashed construction lines.No marks were awarded if there was reference to reflected rays or reference to the fact that a virtual image 'cannot be put on a screen'.You were asked how you could deduce information from the diagram!

(1 mark)(b) The student now uses a different converging lens. She places the object between the lens and point F on the left. The table shows the set of results that she gets for the distance d and for the magnification produced.

Distance d /cm Magnification

5 1.2

10 1.5

15 2.0

20 3.0

25 6.0Her friend looks at the table and observes that when the distance doubles from 10 cm to 20 cm, the magnification doubles from 1.5 to 3.0. Her friend's conclusion is that:"The magnifi cation is directly proportional to the distance of the object from the lens."Her friend's observation is correct but her friend's conclusion is not correct.(i) Explain, with an example, why her friend's conclusion is not correct.You had to pick any observation about the relationship between values of d that don't give the same relationship between corresponding values for magnification.For example:15 is three times bigger than 5 but 2.0 is not three times bigger than 1.2

(2 marks)(ii) Write a correct conclusion.When the distance increases the magnification increases. Accept 'there is a (strong) positive correlation between d and magnification' but do not accept any response in terms of proportion or inverse proportion

(1 mark)

(iii) The maximum range of measurements for d is from the centre of the lens to F on the left. The student cannot make a correct conclusion outside this range. Explain why.The student has no evidence/data/readings outside this range.


Q11.The diagram shows a lens, the position of an object and the position of the image of the object.

(a) What type of lens is shown?Convex lens or converging lens

(1 mark)(b) What is the name of the points, F, shown each side of the lens?Focal points or principal foci (plural of focus)

(1 mark)(c)(i) The image is real and can be put on a screen. How can you tell from the diagram that the image is real?The image point is formed where rays (of light) intersect / meet / cross.

(1 mark)(ii) Draw a ring around a word in the box below which best describes the image produced by the lens.

(1 mark)(d) A student investigates the relationship between the distance from the object to the lens and the magnification produced by the lens. The student's results are given in the table. The student did not repeat any measurements.

Distance/mm Height of object/mm Height of image/mm Magnification

produced

40 20 58 2.9

50 20 30 1.5

60 20 20 1.0

70 20 14 0.7

80 20 12 0.6

90 20 10 0.5The student plots the points for a graph of magnification produced against distance.

(i) Draw a line of best fit for these points.See graph - smooth curve going through the points - NOT a dot-to-dot straight line joining of the points!

(1 mark)(ii) Complete the following sentence by drawing a ring around the correct word in the box. "A line graph has been drawn because both variables are described as being ...."

(1 mark)(iii) Describe the relationship between magnification produced and distance.As distance increases, magnification decreases OR there is a negative correlation.Second mark is for more detail relating to the graph shape...The magnification falls steeply between 40 and 50 cmOR magnification begins to level out after / at 70 cm No mark for saying it is inversely proportional.


GCSE Level Optics Questions

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