2 5,4 shows a ray of light entering and passing along an optical fibre Fig. 54 ) Calculate the refractive index of the glass in the optical fibre. wether inal refractive index = on... L502. (b) Explain why the ray of light is totally internally reflected at A. “claunar nul Cision i therm. Lo on tear L a (c) Both optical fibre and copper wire are used to transmit data ed) ae Optical fibre is cheaper and can carry more data per second than copper wire. State one other advantage of using optical fibre rather than copper wire to transmit data, eucies 2015 sosaraiMns [Turn over‘ GL ) The student performs another experiment with a semicircular glass block and a ray of white light. Fig. 10.2 shows the path taken by this ray of light as it enters the glass at P until it hits the straight edge at Q. semicircular glass block white light N| Fig. 10.2 The student finds that there is no change in direction as the ray enters the glass at P and that no light passes out of the glass at Q. (i) Explain why the ray does not change direction at P. th eHlesa. ctrcsaiatheedte, Ap foot dee cithea gle slbaly uber. fos Aas (ii) Explain why no ae passes out of the glass at Q. hte letrinndletrcde entre cetp hain treaccthee. “ epee emnpgletc “Pos center ten..8 Glo hcade.... essnled cad. eset Bt: (iii) Gn Fig. 10.2, draw the complete path followed by this ray. io) (iv) The student directs the ray of white light into the glass along different paths, so that the angle @ is slowly reduced Describe what happens to the ray at.Q. wiles tghhe Odsisadese fe asaletiars uheedl ate For Examiners Use Les 2013 sosarzanuyia [Turn over226 (@) State the speed of light in air, 2x10” mb {b) Fig. 10.1 shows a ray of blue light passing from air into a glass biock and refracting at the surface. blue wi 1 glass block Fig. 10.1 (not to scale) (As the light enters the glass, state what happens to 1. the speed of tha light, wthtacte 2. the frequency of the light, 2 of “8. the wavelength of the light. {tl Sli (On Fig, 10.1, mark and labet the angle of incidence jand the angle of rafraction. [2 {) The tefraciive index of glass for blue light is 1.5. {i) Aray of blue light strikes the suriace of a glass block at an 2 of incidence of 89°. Caloulate the angle of refraction of the light in the block.4g hntas it passes through a glass prism. (a) Fig, 10.1 shows the path of @ 12 of blue lig Fig. 10.1 (i) Siate the wave term used to describe what happens to the ray of light at A. > 0:1, calculate the refractive index of the glass. af 45° 2. oae ee) refractive index = (ii) Using angles from Fig. 1 [3] Explain why the ray does not emerge from the prism at B. i) " Cina Loa hh gc db tad asad. tila ip.tte ppb lesaatitins aandatcal, Sybede{2) (iv) Fig. 10.2 shows a second, horizontal, ay of blue light striking the prism at point C. On Fig. 10.2, continue the path of the second ray through and out of the glass prism. [2] Fig. 10.2 uctes 2012 . = ' sosaranmaiste [Turn overi . 54 42: Fig. 3.1 shows light entering a transparent block. ~_ transparent block 3.4 (not to scale) The light enters the block at an angle @ to the normal and travels through the block unti it meets the bottom surface. The angle between the ray in the block and the vertical side of the block is g. {a) Light travels more slowly in the block than in air. (i) Explain how Fig. 3.1 shows this. whet, art tne leanne kesh erectile Df ee espe ehonaypiely then gh drnecere...achesth fi lle. che leaner. ata. (ii) State what happens to the wavelength of the light and what happens to the light as it enters the block. [ the frequency wavelength Lacan. 7 Che frequency (b) The refractive index of the transparent material is 1.6. Angle is 45°. (i) Determine angle 9. 5054/22/01N/21 @UCLES 2021