Figure shows a simple version of a zoom lens. The converging lens has focal length f1 and the diverging lens has focal length f2 = -Ι f2Ι. The two lenses are separated by a variable distance d that is always less than f1. Also, the magnitude of the focal length of the diverging lens satisfies the inequalityΙ f2Ι7( f1 - d). To determine the effective focal length of the combination lens, consider a bundle of parallel rays of radius r0 entering the converging lens. (a) Show that the radius of the ray bundle decreases to r′ 0 = r0( f1 - d)/f1 at the point that it enters the diverging lens. (b) Show that the final image I′ is formed a distance s′ 2 =If2I( f1 - d)/(I f2I- f1 + d) to the right of the diverging lens. (c) If the rays that emerge from the diverging lens and reach the final image point are extended backward to the left of the diverging lens, they will eventually expand to the original radius r0 at some point Q. The distance from the final image I′ to the point Q is the effective focal length f of the lens combination; if the combination were replaced by a single lens of focal length ƒ placed at Q, parallel rays would still be brought to a focus at I′. Show that the effective focal length is given by f = f1If2I/(I f2)- f1 + d). (d) If f1 = 12.0 cm, f2 = -18.0 cm, and the separation d is adjustable between 0 and 4.0 cm, find the maximum and minimum focal lengths of the combination. What value of d gives f = 30.0 cm?
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- Compute the focal length of a diverging thin lens made of flint glass, whose refractive index is 1.66 and is immersed in air having refractive index 1. The radii of the spherical surfaces of the lens are 10 cm and 20 cm. Select one: O -30 cm O O -10 cm 30 cm 10 cmarrow_forwardThere is a lens combinations between two converging lenses that have focal lengths of f1=13 cm (lens 1) and f2=16 cm (lens 2). They are separated by 56 cm along a horizontal line. There is a lit candle (height ho) placed 36 cm in front of the lens 1 (f1=13 cm). Thus, the separation between the candler and the second lens (f2=16 cm) is 92 cm (image attached) Please draw ray diagram and estimate location of final imagearrow_forwardThere is a lens combinations between two converging lenses that have focal lengths of f1=13 cm (lens 1) and f2=16 cm (lens 2). They are separated by 56 cm along a horizontal line. There is a lit candle (height ho) placed 36 cm in front of the lens 1 (f1=13 cm). Thus, the separation between the candler and the second lens (f2=16 cm) is 92 cm Please calculate actual postion of final image. Is it real/imaginary?arrow_forward