Exampro GCSE Physics P3 - Medical Applications of Physics Self Study Questions - Higher tier Name: Class: Author: Date: Time: 90 Marks: 90 Comments: Page of 32
Q. The diagram shows a glass prism. (i) Explain why refraction has not occurred at point X....... () (A) Give the full name for the process which has occurred at point Y.... () (B) Explain why this process has occurred.......... (2) (Total 4 marks) Page 2 of 32
Q2. Pigs have a layer of fat in their skin. Underneath the fat is a layer of muscle. Ultrasonic waves are used to measure the thickness of the layer of fat. An ultrasound transmitter and detector are attached to the skin of the pig. (a) Explain why ultrasound can be used to measure the thickness of the layer of fat............. (2) (b) The oscilloscope does not measure distance directly. (i) What does the oscilloscope measure in this case?...... () What other information is needed to calculate the thickness of the layer of fat in a pig?...... () (Total 4 marks) Page 3 of 32
Q3. 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 size and position of the image changes: (i) when the object OB is moved towards the focal point F... when the object OB is moved past F to a point nearer the lens than the focal point... (4) (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................ (3) (Total 7 marks) Q4. (a) The diagram shows a lens used as a magnifying glass. The position of the eye is shown and the size and position of an object standing at point O. (i) What type of lens is shown in the diagram?... () Page 4 of 32
Two points are marked as F. What are these points?... () (iii) What is the name of the straight line which goes through the point F, through the point L at the centre of the lens, and through the point F on the other side?... () (iv) On the diagram, use a ruler to construct accurately the position of the image. You should show how you construct your ray diagram and how light appears to come from this image to enter the eye. (5) (v) The image is virtual. What is a virtual image?...... () Page 5 of 32
(b) The lens shown in the diagram in part (a)(iv) can be used in a camera to produce a real image. Explain why a real image must be produced in a camera and how the object and the lens are positioned to produce a real image which is smaller than the object. Do not draw a ray diagram as part of your answer................... (3) (Total 2 marks) Q5. The picture shows a pre-natal scan obtained using ultrasonic waves. (i) Explain how ultrasonic waves are used to produce the image of an unborn baby............. (2) Give another use for ultrasonic waves.... () (Total 3 marks) Page 6 of 32
Q6. Ultrasound can be used in industry for detecting internal cracks in metals. (a) State two features of ultrasound.... 2... (2) (b) The diagram shows an ultrasound transmitter and detector fixed to the front of a metal block. The block has an internal crack. The diagram below shows the screen of the oscilloscope connected to the detector. (i) Explain why pulse A and pulse B occur....... (2) The metal block is 20 mm from front to back. What is the distance, in mm, from the front of the block to the internal crack? Distance =... mm () (Total 5 marks) Page 7 of 32
Q7. (a) The diagrams show oscilloscope traces for the same musical note played on two different instruments. The oscilloscope settings are not changed. (i) How can you tell, from the diagrams, that it is the same musical note?...... () How can you tell, from the diagrams, that the musical note has been played on different instruments?...... () (b) This passage is from an electronics magazine. Electronic systems can be used to produce ultrasound waves. These waves have a higher frequency than the upper limit for hearing in humans. Ultrasound waves are partially reflected when they meet a boundary between two different media. (i) Approximately what is the highest frequency that humans can hear? State the number and the unit.... () What does the word media mean when it is used in this passage?...... () Page 8 of 32
(iii) What happens to the ultrasound which reaches the boundary between two different media and is not reflected?............ (2) (Total 6 marks) Q8. The diagram shows a ray of light passing through a diverging lens. Page 9 of 32
(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 0 of 32
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) (b) Describe the nature of this image relative to the object. (2) (Total 6 marks) Page of 32
Q0. (a) The diagram shows the inside of the eye of a person with perfect vision. Complete the sentence. The process by which the cornea and lens change the direction of the light is called.... () Page 2 of 32
(b) (i) Not everyone has perfect vision. A short-sighted person can only clearly see objects which are close. Light from distant objects meets in front of the retina. The diagrams show how an additional lens will correct short-sightedness. Uncorrected vision Vision corrected with a diverging lens The following diagram shows what happens when light from a close object enters the eye of a long-sighted person. Light fails to come to focus on the retina What type of additional lens will correct the vision of a long-sighted person?... () The additional lens changes the direction of the light before it enters the eye. Why does this correct the person s vision? () Page 3 of 32
(c) Read this passage from a magazine. Explain how these glasses are adjusted for a short-sighted person and how this adjustment allows the person to see distant objects clearly. (3) (Total 6 marks) Page 4 of 32
Q. (a) The diagram shows a microphone being used to detect the output from a loudspeaker. The oscilloscope trace shows the wave pattern produced by the loudspeaker. (i) How many waves are produced by the loudspeaker in 0.000 seconds?... () How many waves are produced by the loudspeaker every second? Assume the input to the loudspeaker does not change. () (iii) A person with normal hearing cannot hear the sound produced by the loudspeaker. Explain why. (2) Page 5 of 32
(b) The diagram shows how a very high frequency sound wave can be used to check for internal cracks in a large steel bolt. The oscilloscope trace shows that the bolt does have an internal crack. (i) Explain what happens to produce pulse A and pulse B. (2) Use the information in the diagram and the equation in the box to calculate the distance from the head of the bolt to the internal crack. distance = speed time Speed of sound through steel = 6000 m/s Show clearly how you work out your answer. (3) (Total 9 marks) Page 6 of 32
Q2. (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 7 of 32
(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) Q3. 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 8 of 32
(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) Q4. (a) Human eyes and digital cameras both have parts with the same function. Complete the missing parts in the table below. Details of part Part of eye Part of digital camera Refracts light to produce an image Cornea and lens Lens Images are focused here Retina... Variable opening where light enters... Aperture (2) Page 9 of 32
(b) Long sight is a defect of the human eye. State two causes of long sight.... 2... (2) (c) Long sight can be corrected by wearing spectacles with converging (convex) lenses. A lens in these spectacles has a power of +3.2 dioptres. Calculate the focal length of this lens. Use the correct equation from the Physics Equations Sheet. Focal length =... metres (2) (d) The figure below shows a ray of light passing through a converging (convex) lens. (i) Use the information in the figure above to calculate the refractive index of the glass used to make the lens. Use the correct equation from the Physics Equations Sheet. Refractive index =... (3) Page 20 of 32
Different lenses of the same power can be made using glass of a different refractive index. State one advantage of making spectacles using lenses made from glass of a higher refractive index. () (Total 0 marks) Page 2 of 32
M. (i) (incident) ray along the normal or (incident) ray at 90 (to the surface) (A) total internal reflection all three words required do not credit total internal refraction (B) EITHER angle of incidence is greater than the critical angle or angle of incidence is greater than 42 2 OR angle of incidence is 45 [4] M2. (a) (ultrasound) waves reflected accept bounce off at boundary / from muscle (b) (i) time speed of (ultrasound) waves [4] M3. (a) (i) Image distance increases Image size increases Remains inverted Remains real for mark each 2 Image distance decreases Image size decreases Becomes upright Becomes virtual for mark each 2 Page 22 of 32
(b) Move lens with respect to film Closer for distant objects Further for near objects for mark each 3 [7] M4. (a) (i) converging / convex / biconvex (iii) focal (points) or foci accept focuses or focus (point) (principal) axis (iv) all lines drawn with a ruler for full marks no ruler, penalise mark from first four last mark can still be awarded double refraction drawn could get 4 out of 5 marks ray that continues from the top of the object through L to the eye horizontal ray from the top of the object, refracted by the lens and continued through F on the r.h.s. to the eye back projections of these rays (shown as dotted lines) image 25 mm high at 6 mm left of L (tolerance mm ± vertically, 2 mm ± horizontally) at least one arrow shown on real ray and towards the eye but do not credit if contradicted by other arrow(s) Page 23 of 32
(v) formed where imaginary rays intersect / cross or not formed by real rays accept (virtual image) is imaginary accept cannot be put on screen do not credit just is not real (b) (the image) needs to fall on film / sensors / LDRs / CCDs accept just charged couples do not credit solar cells do not accept virtual image cannot be stored either to cause a (chemical) reaction or to be digitalised for credit response must be appropriate to camera type object (should be) on the far side of F / the focus (from the lens) or more than the focal length (away from the lens) allow beyond the focus or object should be more than twice the distance / 2F (from the lens) (2 marks) or more than twice the focal length (away from the lens) (2 marks) [2] M5. (i) (partly) reflected when they hit a (boundary between two) different media or substance or tissue accept named substances do not accept bounce back time taken for reflected wave (to return) is used to produce the image any one from: cleaning a delicate mechanism / jewellery do not accept cleaning welding plastics cutting textiles mixing emulsion paints sonar motion sensors (in burglar alarms) do not accept burglar alarms Page 24 of 32
removing dental plaque industrial quality control breaking up kidney stones treating injuries [3] M6. (a) any two points: do not credit features which are true of sound in general eg longitudinal waves humans cannot hear ultrasound it has a very high frequency / pitch do not credit just has a high frequency / pitch above the (upper) limit for humans / above 20 000 Hz 2 (b) (i) ultrasound / waves are reflected...are bounced is insufficient, but...echo is acceptable Pulse A indicates / is the crack Pulse B indicates / is the back (of the block or crack) need to mention both A and B to get this mark 90 (mm) accept any answer in the range 88 92 (mm) [5] M7. (a) (i) same frequency / period / pitch / wavelength ignore references to amplitude differences in waveform / shape / quality accept the diagrams are not identical Page 25 of 32
(b) (i) 20 000 Hz / hertz or 20 khz / kilohertz in both cases, if the symbol rather than the name is used, it must be correct in every detail material(s) / substance(s) (through which sound travels) (iii) is absorbed accept (some) sound (energy) is transformed / transferred as heat / thermal energy is transmitted accept is refracted accept changes speed accept changes velocity do not accept is diffracted do not accept is diffused do not accept is dissipated [6] M8. (a).59 accept an answer that rounds to this allow mark for correct substitution into correct equation ie refractive index = 2 (b) 2 lines correctly drawn from the top of the pin through the lens allow mark for each 2 position of image correct image must be upright [5] Page 26 of 32
M9. (a) any two for mark each deduct () from the first two marks if a ruler has not been used but the intention is clear ray from the object's arrowhead through centre of lens parallel to the axis then, when it reaches the lens, through F on the right through F on the left then, when it reaches the lens parallel to the axis example of a 4 mark response if more than two construction lines have been drawn all must be correct to gain 2 marks construction lines drawn as dashed lines do not score credit 2 image shown as vertical line from axis to where their rays intersect image need not be marked with an arrowhead but, if it is, it must be correct ray direction shown only one correct direction arrow needed but there must not be any contradiction (b) any two from: inverted accept upside down magnified accept bigger real accept not virtual / not imaginary one correct feature gains mark ignore any reference to position an incorrect feature negates a correct response 2 [6] Page 27 of 32
M0. (a) refraction (b) (i) converging accept convex cause the light (rays) to meet on / focus at retina / back of eye do not accept hit the retina only (c) silicone is removed from the lens(es) lens(es) thinner in / at the middle (than at the edge) or lens(es) became concave / diverging diverges(s) the light which (now) meets / focuses at the retina / back of the eye [6] M. (a) (i) 3 30 000 or 0 000 their (a)(i) correctly calculated (iii) any two from: frequency is above 20 000 (Hz) accept the frequency is 30 000 frequency is above the upper limit of audible range upper limit of audible range equals 20 000 (Hz) ignore reference to lower limit it is ultrasound/ultrasonic 2 (b) (i) wave (partially) reflected at crack to produce A and end of bolt to produce B accept at both ends of the crack Page 28 of 32
0.075 (m) allow 2 marks for time = 0.000025 allow mark for time = 0.000025 answers 0.5 or 0.05 or 0.09 gain 2 marks answers 0.8 or 0.03 gain mark the unit is not required but if given must be consistent with numerical answer for the available marks 3 [9] M2. (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 2 an arrow showing the position and correct orientation of the image for their rays 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 (x) 3.0 accept 3.0 to 3.5 inclusive or correctly calculated allow mark for correct substitution into equation using their figures ignore any units 2 Page 29 of 32
(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] M3. (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 30 of 32
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] M4. (a) CCD / charged coupled device ignore sensor do not allow film pupil do not allow iris (b) the eye(ball) being too short the (eye) lens being unable to focus (an image at the retina) or the (ciliary) muscles being unable to change the shape of the lens sufficiently accept cornea / lens is not curved enough accept lens is not powerful enough or too weak accept lens being unable to accommodate (c) 0.3(25) allow mark for correct substitution, ie 2 (d) (i).4 allow 2 marks for allow 2 marks for.39 an answer of 0.72 gains 2 marks allow mark for correct substitution, ie allow mark for both sine values correctly calculated ie 0.5 and 0.358 ignore any units 3 the lenses can be made thinner allow the lenses / spectacles / glasses are lighter allow uses less glass [0] Page 3 of 32
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