A bright object 50 mm high stands on the axis of a concave mirror of focal length 100 mm and at a distance of 300 mm from the concave mirror. How big will the image be ?
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Height of the object (h) = 50 mm Focal lenght of the mirror (f) = -100 mm Object distance (u) = -300 mm 1/v + 1/u = 1/f 1/v = 1/f - 1/u 1/v = 1/(-100) - 1/(-300) 1/v = -1/100 + 1/300 1/v = (-3 + 1)/300 1/v = -2/300 v = 300/-2 v = -150 mm Therefore, the image will be formed 150 mm away from the pole. magnification (m) = h '/h = - v/u h ' = - (v)(h)/u h ' = - (-150)(50) / (-300) h ' = -7500/300 h ' = -25 mm Therefore the height of the image will be 25 mm