Question

An object is 19.0 cm to the left of a lens with a focal length of +9.5 cm. A second lens of focal length +12.5 cm is 29.5 cm to the right of the lens. Find the location and size of the object of height 1.0 cm. Location with respect to the second lens? What is the height (absolute value) of the image?

Answer 1

From lens formula 1/f = 1/u + 1/v Rightarrow 1/v = 1/f - 1/u = 1/9.5 - 1/19 1/v = 19 - 9.5/9.5 times 19 = 9.5/9.5 times 19 Rightarrow v = 19cm since convex lens image is inverted and red Because magnification m = -v/u = 19/19 = -1 Therefore same dimensions i.e., h = 1 cm ii) u = 10.5, f = 12.5 cm from lens formula 1/f = 1/u + 1/v 1/v = 1/f - 1/u = 1/12.5 - 1/10.5 v = -65.62 cm m = -v/u = 65.625/10.5 = 6.25, h = 6.25 virtual inverted image