9 9 9 14 8 In an optics lesson, a Physics student traces the paths of three s of light near the boundary between medium A and. The student uses a protractor to measure the various angles. Fig. 8.1 illustrates the three measurements. For Examiner s Use 18 17 16 15 2 3 14 4 13 5 12 6 7 1 8 18 17 16 15 14 13 12 1 8 7 6 5 4 3 2 medium A 1 18 17 16 15 2 3 14 4 13 5 12 6 7 1 8 18 17 16 15 14 13 12 1 8 7 6 5 4 3 2 medium A 2 3 18 17 16 15 2 3 14 4 13 5 12 6 7 1 8 18 17 16 15 14 13 12 1 8 7 6 5 4 3 2 medium A Fig. 8.1 UCLES 29 625/31/M/J/9
15 (a) State which is the optically denser medium, A or, and how you can tell this.... For Examiner s Use... [1] (b) State in which medium the light travels the faster, and how you know this....... [1] (c) State the critical angle of medium A....[1] (d) State the full name for what is happening to 3....[1] (e) The refractive index of medium A is 1.49. Calculate the value of the angle of refraction of 1, showing all your working. (f) The speed of light in is 3. 8 m / s. angle of refraction =... [2] Calculate the speed of light in medium A, showing all your working. speed of light =... [2] [Total: 8] UCLES 29 625/31/M/J/9
6 A laser is a device that gives a narrow parallel beam of monochromatic (single-colour) light. Fig. 6.1 shows the light from a laser shining on a triangular glass prism. prism screen light from laser Fig. 6.1 (a) On Fig. 6.1, complete the path of the light until it reaches the screen. [2] (b) What will be seen on the screen?...[1] (c) The beam of light from the laser is replaced by a beam of white light from a lamp. State what is now seen on the screen.......[2] [Total: 5] UCLES 211 625/21/M/J/11
14 8 (a) Fig. 8.1 shows a section of an optical fibre. It consists of a fibre of denser transparent material, coated with a layer of a less dense transparent material. less dense material denser material Fig. 8.1 One within the fibre has been started for you on Fig. 8.1. (i) State and explain what happens to the already drawn, after it reaches the boundary between the materials....[2] (ii) On Fig. 8.1, carefully continue the until it reaches the end of the section of optical fibre. [1] (b) Fibre-optic cables are sometimes used to carry out internal examinations on the human stomach. (i) Suggest one reason why the cable is made of thousands of very thin optical fibres. (ii) Describe briefly how the inside of the stomach is illuminated. UCLES 211 625/31/M/J/11
15 (iii) Describe briefly how the light from the stomach is transferred to the detecting equipment outside the body. [Total: 6] UCLES 211 625/31/M/J/11
8 4 Figs. 4.1 and 4.2 show a semi-circular glass block as s of blue light are directed into the block at different angles. The s are directed towards the centre C of the semi-circle so that no refraction occurs as the s enter the block. For Examiner s Use (a) At the angle shown in Fig. 4.1, no refracted emerges from the block at C. 4 C incident glass reflected Fig. 4.1 (i) Determine the angle of reflection at C. (ii) State the type of reflection occurring at C. angle of reflection =...... [2] (b) 5 C emerges in close to glass surface incident glass reflected Fig. 4.2 Calculate the refractive index of the glass. refractive index =... [3] UCLES 212 625/32/M/J/12
9 (c) The experiment in (b) is now repeated with red light. On Fig. 4.3, draw and label the paths of the reflected and refracted s of red light. The dashed lines show the paths taken by the blue light in (b). For Examiner s Use 5 C red light paths taken by s of blue light in (b) Fig. 4.3 [2] (d) Fig. 4.4 shows a 9 prism used in an optical instrument. Part of the path of a of light passing through the instrument is also shown. Light leaves the instrument along path B. prism path B Fig. 4.4 In the dashed box, draw another 9 prism and complete the path of the light through this box. [2] [Total: 9] UCLES 212 625/32/M/J/12
6 (a) A periscope is an optical instrument containing two mirrors in a long tube. Fig. 6.1 shows the path of a of light through a periscope, without the tube. 9 mirror A normal normal mirror B Fig. 6.1 (i) On Fig. 6.1, 1. use the letter i to indicate clearly the angle of incidence of the striking mirror A, 2. use the letter r to indicate clearly the angle of reflection of the leaving mirror A. [1] (ii) Write down the equation that links i and r. (iii) Suggest a use for the periscope. (iv) State what happens if mirror B is rotated through a small angle. UCLES 214 625/21/M/J/14
8 (a) A of red light passes through a glass block, as shown in Fig. 8.1. 13 glass of red light Fig. 8.1 (i) On Fig. 8.1, clearly label the angle of refraction. [1] (ii) State the name given to the dashed line drawn at 9 to the boundary.... [1] (b) A roadside reflector is made of plastic. It reflects the light from car headlamps. Fig. 8.2 shows part of the path of a of light through the reflector. A roadside reflector Fig. 8.2 The critical angle for the plastic is less than. (i) On Fig. 8.2, complete the path of the of light. [1] (ii) State the term used to describe this type of reflection.... [1] (iii) Explain why the turns though 9 at A.... [1] [Total: 5] UCLES 215 625/21/M/J/15
11 8 (a) A student arranges two prisms as shown in Fig. 8.1. He aims a of red light to hit the surface of one of the prisms at 9. of red light Fig. 8.1 The critical angle for the glass is 42. On Fig. 8.1, draw the path of the light through the prisms. [4] (b) Visible light is one region of the electromagnetic spectrum, as represented in Fig. 8.2. radio waves microwaves infra-red waves visible light ultraviolet waves long wavelength short wavelength Fig. 8.2 (i) Two regions of the electromagnetic spectrum are missing from Fig. 8.2. State the name of the missing region with the longer wavelength. (ii) An infra-red sensor is fitted into a room as part of an intruder alarm system. Explain how the sensor detects a person in the room....[2] (iii) State two properties that are the same for all electromagnetic waves. 1.... 2.... [2] [Total: 9] UCLES 215 625/22/M/J/15