9. n Voorwerp word 15 cm vanaf 'n severe spieel gepleas . Die beeld is die helfte van die grootte van die voorwarp , omgekeerd en reeel . Hoe ver is die beeld vanaf die spieel, en wat is die groote van die krom mingstraal van die spieel? / An object is placed 15 cm from a certain mirror . The image is holf the size of the object , inverted , and real . How for is the image from the mirror , and what is the radius of curvature of the mirror ? [d, = 7,5 cm; r = 10 cm) 10. **Lig val in op een vlak van 'n gelyksydige glas prisma teen 'n hoek van 45,0 . Bereken die hoek wearteen die lig by die teenoorgestelde vlak uittree. Aanvaar dat n = 1,58 . / Light is incident on on equilateral glass prism at 0 45,0 * angle to one face . Calculate the angle at which light emerges from the opposite foce . 45.0 Assume that n = 1,58 . (8 4 = 60.4 -] 11. * *[a) Wat is die minimum brekingsindeks van 'n glas of plastiek prisma wat in verkykers gebruik word sodat totale interne weerkaatsing teen 45 : sal plassvind ? (b) Sal die verkyker werk indien die prismas onder water gehou word ? (Aanveer n = 1,50) (c) Wat is die minimum n sodat die prismas wel onder water sal werk ?/ (@) What is the minimum index of refraction for a glass or plastic prism to be used in binoculars so that totol internal reflection occurs at 45 :? (b) Will binoculars work if its prisms (assume n = 1,50 ) are immersed in water ? (c) What minimum n is needed if the prisms are immersed in water ? [(o ) n = 1,41 ; (b) no; (c) n = 1,88 ] 12. **Die grenshoek van 'n sekere stuk plastiek in lug is @ = 37,3:. Wat is die grenshoek van dieselfde plastiek indien dit onder water gehou word ? / The critical angle of a certain piece of plastic in air is 0 , = 37,3 :. Whot is the critical angle of the some plastic if it is immersed in water ? /8 , = 53,7 :)