Chapter 4 Light Name: Class: Date: Time: 43 minutes Marks: 43 marks Comments: Page of 53
A person can see an image of himself in a tall plane mirror. The diagram shows how the person can see his hat. (a) Which point, A, B or C, shows the position of the image of his hat? Write the correct answer, A, B or C, in the box. (b) (c) On the diagram, use a ruler to draw a light ray to show how the person can see his shoe. Which one of the words in the box is used to describe the image formed by a plane mirror? Draw a ring around the correct answer. () (3) imaginary real virtual () (Total 5 marks) 2 (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) Name the point where the rays come together.... () Page 2 of 53
(iii) What word can be used to describe this type of lens?... () (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? Point... () Explain your answer to part (b)(i)....... () (iii) What word can be used to describe this type of lens?... () (c) Complete the following three sentences by crossing out the two lines in each box which are wrong film In a camera a converging lens is used to produce an image on a 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) Page 3 of 53
(d) Explain the difference between a real image and a virtual image................... (3) (Total 3 marks) 3 The ray diagram shows the image formed by a concave mirror. Use the equation in the box to calculate the magnification. Show clearly how you work out your answer....... Magnification =... (Total 2 marks) Page 4 of 53
4 A student investigated the refraction of light as it passed out of a clear plastic block into the air. Diagram shows the apparatus the student used. Diagram (a) The angle i is the angle of incidence. Use the letter r to mark the angle of refraction on Diagram. () (b) The student measured the angle of refraction for different angles of incidence. The results are shown in the graph. Angle of incidence in degrees (i) One of the results seems to be anomalous. Draw a ring around the anomalous data point on the graph. () Page 5 of 53
The student did measure the angles of incidence accurately. What is likely to have caused the anomalous result? () (iii) What conclusion can the student make from the results shown in the graph? Draw a ring around the correct answer to complete each sentence. less than The angle of refraction is equal to the angle of incidence. greater than () (c) Light travelling from water into air is refracted in the same way as when light travels from plastic into air. Diagram 2 shows a large bottle, filled with water. The bottle is made from clear plastic. Draw on Diagram 2 the path of the light ray as it passes out of the bottle into the air. Diagram 2 (2) Page 6 of 53
(d) In some countries, people are too poor to pay for electricity. Some people living in small houses with no natural light use bottles filled with water as a sort of light bulb. The bottles are fitted into small holes in the roof of the house. Sunlight goes into the bottle of water. When the light leaves the bottle, the light is refracted, causing sunlight to spread into the room. Diagram 3 (i) What is likely to be the most important outcome of using this simple device to provide light? Tick ( ) one box. People will have enough light to work inside their homes. Fewer plastic bottles will be thrown into rubbish tips. Plastic bottles will increase in value. () Suggest one disadvantage of using this device compared with using a light bulb. () (Total 8 marks) Page 7 of 53
5 (a) Figure shows a ray of light entering a glass block. (i) The angle of incidence in Figure is labelled with the letter i. On Figure, use the letter r to label the angle of refraction. () Figure 2 shows the protractor used to measure angles i and r. What is the resolution of the protractor? Tick ( ) one box. degree 5 degrees 0 degrees () Page 8 of 53
(iii) The table shows calculated values for angle i and angle r from an investigation. Calculated values sin i = 0.80 sin r = 0.50 Use the values from the table to calculate the refractive index of the glass. Use the correct equation from the Physics Equations Sheet. Refractive index =... (2) (b) The diagrams below show a ray of light moving through glass. Which diagram correctly shows what happens when the ray of light strikes the surface of the glass at the critical angle? Tick ( ) one box. () Page 9 of 53
(c) A concave (diverging) lens is fitted into a door to make a security spyhole. Figure 3 shows how this lens produces an image. (i) State one word to describe the nature of the image in Figure 3.... () Use data from Figure 3 to calculate the magnification of the image. Use the correct equation from the Physics Equations Sheet. Magnification =... (2) Page 0 of 53
(iii) What is another use for a concave lens? Tick ( ) one box. A magnifying glass Correcting short sight To focus an image in a camera () (Total 9 marks) 6 The diagram shows a lens being used as a magnifying glass. (a) (i) What type of lens is shown in the diagram? Draw a circle around your answer. concave converging diverging () Page of 53
Use the equation in the box to calculate the magnification produced by the lens. The object and image in the diagram have been drawn to full size. Show clearly how you work out your answer. Magnification =... (2) (b) The diagram shows how the image changes when the object has been moved closer to the lens. Complete the following sentence by drawing a ring around the correct line in the box. increases Moving the object closer to the lens does not change the magnification produced decreases by the lens. () (Total 4 marks) Page 2 of 53
7 The diagram shows a periscope being used to see over the heads of a crowd of people. The periscope has been made using two plane mirrors. (a) (b) Using a ruler, complete the diagram to show how the second ray of light from a distant object reaches the person s eye. How big is the image produced by the periscope compared to the size of the object? (2)... () (Total 3 marks) Page 3 of 53
8 A puppy can see an image of himself in a plane mirror. The diagram shows how the puppy can see his disc. (a) (b) On the diagram, use a ruler to draw a ray to show how the puppy can see the top of his ear, which is marked as T. What is a plane mirror?... (3)... () (Total 4 marks) 9 The ray diagram shows a converging lens being used as a magnifying glass. The diagram has been drawn to scale. Page 4 of 53
(a) What name is given to the type of lens used as a magnifying glass?... () (b) Calculate the magnification produced by the lens. Write down the equation you use, and then show clearly how you work out your answer................... Magnification =... (2) (c) Describe the image produced by a magnifying glass.......... (3) (Total 6 marks) 0 (a) The diagram shows a ray of light being reflected by a plane mirror. Which of the angles, a, b, c or d, is: the angle of incidence; the angle of reflection? (2) Page 5 of 53
(b) The diagram shows a road junction seen from above. A mirror placed at the side of the road allows the driver of car X to see car Y. Using the same mirror symbol given in part (a), draw a plane mirror to show how it should be placed so that the driver of car X can see car Y. (2) (Total 4 marks) 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. Use the equation in the box to calculate the magnification produced by the lens shown in the diagram. Show clearly how you work out your answer. Magnification =... (2) Page 6 of 53
The points F are at equal distances on either side of the centre of the lens. State the name of these points. () (iii) Explain how you can tell, from the diagram, that the image is virtual. () (b) The student now uses a different converging lens. He places the object between the lens and point F on the left. The table shows the set of results that he gets for the distance d and for the magnification produced. Distance d measured in cm Magnification 5.2 0.5 5 2.0 20 3.0 25 6.0 His friend looks at the table and observes that when the distance doubles from 0 cm to 20 cm, the magnification doubles from.5 to 3.0. His friend s conclusion is that: The magnification is directly proportional to the distance of the object from the lens. His friend s observation is correct but his friend s conclusion is not correct. (i) Explain, with an example, why his friend s conclusion is not correct. (2) Page 7 of 53
Write a correct conclusion. () (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. () (Total 8 marks) 2 (a) Light waves transfer energy. (i) Complete the following sentence. The oscillations producing a light wave are... to the direction of the energy transfer by the light wave. () The apparatus in the diagram shows that light waves transfer energy. Describe how switching the desk lamp on and off shows that light waves transfer energy. You do not need to describe the energy transfers. (2) Page 8 of 53
(b) A student holds a wrist watch in front of a plane mirror. The student can see an image of the wrist watch in the mirror. The diagram shows the position of the wrist watch and the mirror. Draw a ray diagram showing how the image of the wrist watch is formed. Mark the position of the image. (4) (c) The image of the wrist watch seen by the student is virtual. What is a virtual image?...... () (Total 8 marks) Page 9 of 53
3 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. Use the equation in the box to calculate the magnification produced by the lens shown in the diagram. magnification = Show clearly how you work out your answer. Magnification =... (2) The points F are at equal distances on either side of the centre of the lens. State the name of these points. () (iii) Explain how you can tell, from the diagram, that the image is virtual. () Page 20 of 53
(b) The student now uses a different converging lens. He places the object between the lens and the point F on the left. The table shows the set of results that he gets for the distance d and for the magnification produced. Distance d measured in cm Magnification 5.2 0.5 5 2.0 20 3.0 25 6.0 His friend looks at the table and observes that when the distance doubles from 0 cm to 20 cm, the magnification doubles from.5 to 3.0. His friend s conclusion is that: The magnification is directly proportional to the distance of the object from the lens. His friend s observation is correct. His friend s conclusion is wrong. (i) Explain using data from the table why his friend s conclusion is wrong. (2) Write a correct conclusion. () Page 2 of 53
(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. () (Total 8 marks) 4 (a) Figure shows a diagram of a human eye. Label the parts A and B on Figure. (2) (b) State the function of the iris....... () Page 22 of 53
(c) Figure 2 shows light rays travelling into the human eye. (i) Give the name of the defect of vision shown in Figure 2. () A concave (diverging) lens can be used to correct the defect of vision shown in Figure 2. Complete the ray diagram in Figure 3 to show how a concave lens produces an image of the object. Use an arrow to represent the image. (3) Page 23 of 53
(d) It is important that muscles can change the power of the lens in the eye. State why.... () (e) The power range of an eye lens is the difference between the maximum and minimum power of the lens. Figure 4 shows how the power range of an eye lens changes with age. (i) Use data from Figure 4 to calculate the maximum change that can happen to the focal length of the eye lens for a 60-year-old person. Use the correct equation from the Physics Equations Sheet. Give the unit. Maximum change in focal length =... unit... (2) Page 24 of 53
Compare the change in power range of the eye lens between the ages of 0 and 30 with that between the ages of 50 and 70. (3) (iii) Use Figure 4 to suggest the power range of the eye lens for a 90-year-old person. Power range =... dioptres () (Total 4 marks) 5 Figure shows how a ray of light from a laser travels along an optical fibre. Figure (a) Why does the ray of light stay within the optical fibre?...... () (b) The material used to make the optical fibre has a refractive index of.50. Calculate the critical angle of this material. Use the correct equation from the Physics Equations Sheet............. Critical angle =... degrees (2) Page 25 of 53
(c) Different wavelengths of light can be used to transmit information along optical fibres. Figure 2 shows how the percentage of incident light transmitted through a fibre varies with the wavelength of light and the length of the fibre. Figure 2 Wavelength 0 7 metres Compare the percentages of incident light transmitted through the two different fibres over the range of wavelengths shown............................ (3) (Total 6 marks) Page 26 of 53
6 (a) The diagram shows a converging lens being used as a magnifying glass. (i) On the diagram, use a ruler to draw two rays from the top of the object which show how and where the image is formed. Represent the image by an arrow drawn at the correct position. (3) Use the equation in the box to calculate the magnification produced by the lens. Show clearly how you work out your answer. Magnification =... (2) Page 27 of 53
(b) A camera also uses a converging lens to form an image. Describe how the image formed by the lens in a camera is different from the image formed by a lens used as a magnifying glass............. (2) (Total 7 marks) 7 The diagram shows a ray of light passing through a diverging lens. Page 28 of 53
(a) Use the information in the diagram to calculate the refractive index of the plastic used to make the lens. Write down the equation you use, and then show clearly how you work out your answer................... Refractive index =... (2) (b) The focal length of the lens is 5 cm. A student looking through the lens sees the image of a pin. Complete the ray diagram below to show how the image of the pin is formed. (3) (Total 5 marks) Page 29 of 53
8 A student investigated the refraction of light as it passes into and out of a clear plastic block. Diagram shows the apparatus the student used. Diagram (a) Diagram 2 shows the same apparatus. Use a ruler to draw on Diagram 2 the path of the light ray. Diagram 2 (2) Page 30 of 53
(b) The student measured the angle of refraction (r) for different angles of incidence (i) for light entering the plastic block. The results are shown in Graph. Angle of incidence (i) in degrees (i) What two conclusions can be made about the relationship between the angle of incidence and the angle of refraction from Graph?... 2.... (2) Page 3 of 53
Graph 2 shows the student s results for light passing from air into plastic. The graph also shows the results for light passing from air into water. Angle of incidence (i) in degrees How does the refraction of light passing from air into water compare to the refraction of light passing from air into plastic? () Page 32 of 53
(c) In some countries people are too poor to pay for electricity. Some people living in small houses with no natural light are using bottles filled with water instead of light bulbs. The bottles are fitted into small holes in the roof of the house. Sunlight refracts as it passes into and out of the bottle, causing light to spread into the room. This simple device gives about the same amount of light as a 50 W light bulb. Diagram 3 (i) Suggest one way this simple device can help improve the lives of the people using it. () The increasing use of energy resources to generate electricity within developed countries has ethical implications. Suggest one ethical implication. () (Total 7 marks) 9 When glass is placed in a liquid of the same refractive index, the glass seems to disappear. This method can be used to determine the refractive index of small pieces of glass. Page 33 of 53
(a) The refractive index of some types of glass and some liquids is given in the table. Type of glass Refractive index Liquid Refractive index Bakeware glass.47 Methanol.33 Car headlight glass.48 Water.33 Window glass.50 Alcohol.37 Bottle glass.52 Olive oil.47 Spectacle glass.54 Castor oil.48 Lead glass.62 Cinnamon oil.60 (i) Use information from the table to give an example of a type of glass and a liquid where the glass would seem to disappear. Type of glass... Liquid... () What is the range of refractive index of the liquids in the table? From... to.... () (iii) Which type of glass has a refractive index outside the range for the liquids?. () (b) The diagram shows a ray of light travelling from air into glass. (i) What is the name given to the dashed line?. () Page 34 of 53
(iii) Draw, on the diagram, the letter i to label the angle of incidence. Draw, on the diagram, the letter r to label the angle of refraction. () () (i) The value of i is 46 and the value of r is 29. Calculate the refractive index of the glass. Use the correct equation from Section B of the Physics Equations Sheet... Refractive index =... (3) Look at the table in part (a). Name a type of glass that could have been used in part (b).. () (Total 0 marks) 20 Light changes direction as it passes from one medium to another. (a) Use the correct answer from the box to complete the sentence. diffraction reflection refraction The change of direction when light passes from one medium to another is called.... () (b) Draw a ring around the correct answer to complete the sentence. When light passes from air into a glass block, it changes away from the normal. direction towards the normal. to always travel along the normal. () Page 35 of 53
(c) Diagram shows light rays entering and passing through a lens. Diagram (i) Which type of lens is shown in Diagram? Draw a ring around the correct answer. concave convex diverging () In Diagram, what is the point X called?. () (d) A lens acts like a number of prisms. Diagram 2 shows two parallel rays of light entering and passing through prism A and prism C. Diagram 2 Draw a third parallel ray entering and passing through prism B. (4) (e) What two factors determine the focal length of a lens?... 2... (2) Page 36 of 53
(f) A converging lens has a focal length of 20 cm. Calculate the power, in dioptre, of the lens. Use the correct equation from Section B of the Physics Equations Sheet....... Power of the lens =... dioptre (2) (Total 2 marks) Page 37 of 53
Mark schemes (a) C (b) reflection at the mirror of ray from shoe to person s eye may be drawn freehand angle of incidence = angle of reflection judged by eye a ruler must have been used arrow to show correct direction on either incident or reflected ray only one arrow needed but if more drawn must be no contradiction both incident and reflected ray must be shown (c) virtual [5] 2 (a) (i) rays continued to meet on the right hand side of the lens and beyond must be straight lines from the right hand side of the lens ignore details through the lens allow if no arrows meet exactly on the axis negate mark if contradictory arrow(s) added do not need to go beyond the focus for this mark (iii) (principal) focus or focal (point) converging or convex (b) (i) A Page 38 of 53
rays seem to come from this point or words to this effect or shows this on the diagram (iii) diverging or concave (c) film accept any unambiguous method of showing the correct response smaller than further away from (d) any three from: real image can be put on a screen allow film virtual image cannot be put on a screen / film virtual image is imaginary real image is formed where (real) rays cross / converge allow real image has light travelling through it virtual image is where virtual / imaginary rays (seem to) come from or virtual image is where rays seem to come from virtual image formed where virtual rays intersect / cross 3 [3] 3.4 allow mark for correct substitution ie 4 0 or 28 20 [2] 4 (a) angle of refraction correctly identified accept any correct indication (b) (i) result at i = 25 identified Page 39 of 53
(iii) measuring angle of refraction incorrectly accept any practical suggestion that would lead to the angle r being incorrect eg placing the protractor in the wrong place not marking the refracted ray correctly / accurately / ray box has been moved do not accept measured angle i and angle r incorrectly do not accept plotted incorrectly greater than (c) shown refracting out of the bottle with angle of refraction larger than angle of incidence allow mark for refraction shown on correct side of normal with angle of refraction smaller than angle of incidence (d) (i) People will have enough light to work inside their homes 2 accept any sensible suggestion do not accept roof leaks eg does not work at night no control over light cannot switch on and off eg cannot control brightness [8] Page 40 of 53
5 (a) (i) degree (iii).6 allow mark for correct substitution, ie 0.80 / 0.5 provided no subsequent step shown working showing.59(9..) scores zero 2 (b) 2 nd diagram ticked (c) (i) any one correct description: upright virtual diminished. treat multiple words as a list 0.25 allow mark for correct substitution, ie / 4 or 5 / 20 provided no subsequent step shown ignore any unit 2 (iii) Correcting short sight [9] 6 (a) (i) converging Page 4 of 53
(x) 2 allow mark for correct substitution ie 0/5 or 20/0 or 2/ ignore any units 2 (b) decreases [4] 7 (a) reflection shown at both mirrors ray parallel to given ray judge by eye (b) same size [3] 8 (a) reflection at the mirror of ray from tip of real puppy s ear to real puppy s eye () may be drawn freehand accurate () ruler must have been used and the reflected ray is an extension of the straight line from point virtual ear however the virtual part of the line need not be shown arrow to show correct direction () only one arrow needs to be shown but there must be no contradiction example of (3) mark response 3 (b) flat accept it s not curved/bent accept it s straight [4] 9 (a) converging accept convex Page 42 of 53
(b) 3 allow mark for substitution into the correct equation ie 2 (c) bigger accept magnified upright virtual [6] 0 (a) b c correct order only (b) mirror opposite road junction mirror facing correct way, angle correct judged by eye [4] (a) (i) answer in the range 3.0 3. inclusive accept for 3.6.2 or 3.7.2 or 36 2 or 37 2 or 8 6 or 8.5 6 or 0.2 3.4 or 02 34 or answer in the range but with a unit eg 3 cm 2 (principal) focus / focal (point(s)) / foci / focus accept focusses accept focals do not accept focal length Page 43 of 53
(iii) at the intersection of virtual / imaginary rays or where virtual / imaginary rays cross or the rays of (real) light do not cross or the image on the same side (of the lens) as the object or the image is drawn as a dotted line or the image is upright do not accept cannot be put on a screen do not accept any response which refers to reflected rays (b) (i) another correct observation about relationship between values of d () (but) not the same relationship between corresponding values for magnification () example 5 is three times bigger than 5 but 2.0 is not three times bigger than.2 2 when the distance / d increases the magnification increases or the converse accept there is a (strong) positive correlation do not accept any response in terms of proportion / inverse proportion (iii) (student has) no evidence (outside this range) accept data / results / facts for evidence [8] 2 (a) (i) perpendicular accept correct description light off no / slow rotation light on fast(er) rotation accept starts rotating ignore references to energy transfers (b) one ray drawn from wrist watch and reflected by mirror accept solid or dashed lines two rays drawn from wrist watch and reflected by mirror with i = r for both rays judge angles by eye one ray traced back behind mirror accept solid or dashed lines Page 44 of 53
image in correct position judged by eye accept image marked where two reflected rays traced back cross behind the mirror (c) cannot be formed on a screen accept image formed behind the mirror or rays of light seem to come from it but do not pass through it [8] 3 (a) (i) answer in the range 3.0 3. inclusive accept for mark 3.6.2 or 3.7.2 or 36 2 or 37 2 or 8 6 or 8.5 6 or 0.2 3.4 or 02 34 or answer in the range but with a unit eg 3 cm 2 (iii) (principal) focus / focal (point(s)) / foci / focus accept focusses accept focals do not accept focal length at the intersection of virtual / imaginary rays or where virtual / imaginary rays cross or the rays of (real) light do not cross or the image on the same side (of the lens) as the object or the image is drawn as a dotted line or the image is upright do not accept cannot be put on a screen do not accept any response which refers to reflected rays (b) (i) another correct observation about relationship between values of d example 5 is three times bigger than 5 but (but) not the relationship between corresponding values for magnification 2.0 is not three times bigger than.2 Page 45 of 53
when the distance / d increases the magnification increases or the converse accept there is a positive correlation do not accept any response in terms of proportion / inverse proportion (iii) (student has) no evidence (outside this range) accept data / results / facts for evidence [8] 4 (a) A = suspensory ligament B = retina (b) to control the amount of light entering the eye or to control the amount of light incident on the retina allow change the size of the pupil Page 46 of 53
(c) (i) short sight or myopia accept near sight (d) any 2 correct construction lines: construction lines may be dotted or solid construction lines must pass correctly through the lens treat more than 2 construction lines as a list for marking upright image drawn at correct location image must be to the left of the lens upright orientation of image must be clear the image line can be dotted or solid ignore any arrows on construction rays to focus light from objects at different distances accept can see objects (clearly) at different distances. to focus light on the retina is insufficient 2 Page 47 of 53
(e) (i) 0.5 metre(s) / m the unit is not an independent mark an answer 0.5 without a unit or with an incorrect unit scores mark or a substitution 2 = / f with the unit metre(s) / m scores mark 2 0 to 30 decreases linearly or at a constant rate accept from 0 to 30 the decrease is 2.6 / 2.7(D) 50 to 70 falls less rapidly after 60 years accept it decreases at a decreasing rate accept from 50 to 70 the decrease is 3.3 / 3.4(D) 0 to 30 decrease is less than 50 to 70 (iii) 0.8 (D) accept answers in the range of 0.6 to.0 (D) inclusive [4] 5 (a) because the angle of incidence is greater than critical angle accept the light is totally internally reflected (b) 4.8 allow mark for correct substitution, eg.5 = or sin c = or c = sin - 2 (c) (for both fibres) increasing the wavelength of light decreases and then increases the percentage / amount of light transmitted accept for mark: (for both fibres) increasing the wavelength (of light) to 5 (x 0-7 metres), decreases the (percentage) transmission (for both fibres) the minimum transmission happens at 5 (x 0-7 metres) or maximum transmission occurs at 6.5 (x 0-7 metres) accept for a further mark: (for both fibres) increasing the wavelength of the light from 5 (x 0-7 metres) increases the amount of light transmitted increasing wavelength (of light), decreases the percentage transmitted is insufficient on its own Page 48 of 53
the shorter fibre transmits a greater percentage of light (at the same wavelength) accept for mark: Any statement that correctly processes data to compare the fibres [6] 6 (a) (i) two correct rays drawn mark for each correct ray ray parallel to axis from top of object and refracted through focus and traced back beyond object ray through centre of lens and traced back beyond object ray joining top of object to focus on left of lens taken to the lens refracted parallel to axis and traced back parallel to axis beyond object an arrow showing the position and correct orientation of the image for their rays (x) 3.0 or to gain this mark, the arrow must go from the intersection of the traced-back rays to the axis and the image must be on the same side of the lens as the object and above the axis accept 3.0 to 3.5 inclusive 2 correctly calculated allow mark for correct substitution into equation using their figures ignore any units 2 Page 49 of 53
(b) any two from: in a camera the image is: real not virtual inverted and not upright accept upside down for inverted diminished and not magnified accept smaller and bigger accept converse answers but it must be clear the direction of the comparison both parts of each marking point are required 2 [7] 7 (a).59 accept an answer that rounds to this allow mark for correct substitution into correct equation ie refractive index = (b) 2 lines correctly drawn from the top of the pin through the lens allow mark for each 2 2 position of image correct image must be upright [5] 8 (a) refracted into the block, angle r < i refracted correctly out of block, two rays in air parallel judge by eye if first mark not scored allow mark for correct refraction shown as ray leaves the block (b) (i) the angle of refraction is (always) less than the angle of incidence the angle of refraction increases as the angle of incidence increases accept angle i and angle r are not directly proportional accept there is positive correlation (for the same angle of incidence) the angle of refraction in plastic is less than the angle of refraction in water accept (for the same angle of incidence) plastic refracts light more than water accept it is less Page 50 of 53
(c) (i) accept any sensible suggestion to do with being able to see inside (during daylight hours) eg able to (see to) work / cook inside accept to see what they are doing lights up the room is insufficient ignore no need to pay for electricity accept any ethical suggestion, eg fair access to energy for all unequal use of energy resources consequences for the future of decisions made now damage to global environment affects all damage to the environment is insufficient [7] 9 (a) (i) headlight glass and castor oil or bakeware glass and olive oil.60.33 either order (iii) lead (glass) do not accept.62 (b) (i) normal i correctly labelled allow I for i accept with or without arc Page 5 of 53
(iii) r correctly labelled allow R for r (c) (i).48(375 ) accept with or without arc.5 scores 3 marks allow: n = 0.79 / 0.484 for 2 marks n = sin 46 / sin 29 for mark 3 car headlight glass ecf from (c)(i) [0] 20 (a) refraction (b) towards the normal (c) (i) convex principal focus accept focal point (d) (e) parallel on left refracted towards the normal at first surface refraction away from normal at second surface passes through or heads towards principal focus refractive index accept material from which it is made Page 52 of 53
(radius of) curvature (of the sides) accept shape / radius do not accept power of lens ignore thickness / length (f) 5 (dioptre) / 0.2 gains mark 0.05 gains mark 2 [2] Page 53 of 53