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A thin convex lens of focal length 25 cm is cut into towpieces 0.5 cm above the principal axis. The top part is placed at (0,0) and an object placed at (-50 cm , 0) Find the coordinates of the image. |
Answer» SOLUTION :If lens is cut as pwer the statement then its focal length wil not change.  If lens is not cut, then object WOULD be at HEIGHT 0.5 cm from prinicpal axis OO. . From lens equation, `1/f = 1/v - 1/u` `therefore 1/v = 1/f + 1/u =1/25+ (1)/(-50) = (2-1)/(50)` `therefore 1/v = 1/50` `therefore v = 50 cm ` `therefore` Magnification `m = v/u = - (50)/(50) = -1` Thus , image will be formed at 50 cm from optical CENTRE of lens , but 0.5 cm below the edge passing through base of lens which is cut. If optical centre of the lens is TAKEN at origin and X - axis is passing through cut lens then coordinates of image are (50,-1) cm . |
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