(a) List some advantanges of a reflecting telescope, especially for high resolution astronomy. (b) A reflecting type telescope has a large mirror for its objective with radius of curvature equal to `80 cm`. What is the magnifying power of telescope if eye piece used has a focal length of `1.6 cm` ?
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(a) (i) There is no chromatic aberration as the objective is a mirror. (ii) Spherical aberration is reduced using mirror objective in the form of a paraboloid. (iii) Image is brighter compared to that in a refractine telescope. (iv) Mirror requires griding and polishing of only one side. (v) High resolution is resolution is achieved by using a mirror of large aperture (b) Here, `R = 80 cm`. `f_(0) = (R )/(2) = (80)/(2) = 40 cm` and `f_(e) = 1.6 cm`. As magnifying power, `m = (f_(0))/(f_(e))` `:. m = (40)/(1.6) = 25`
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