A 4.5 cm needle is placed 12 cm away from a convex mirror of focal length 15 cm. Give the location of the image and magnification. Describe what happens as the needle is moved farther from the mirror.
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h1 = 4.5 cm, u = - 12 cm, / = 15 cm, v = ? using the equation, 1/f = 1/v+ 1/u we have, 1/15= 1/v+ 1/-12 1/15+1/12=v By solving we get v= +6.6 cm. Now, m= -v/u, m= +6.6 cm/ -12= 0.55 Image will diminish.