Here's the question bank on all the general science topics.
An object, 3.0 cm in height, is placed at a distance of 45.0 cm in front of a concave minor of focal length 30.0 cm, on its principal axis. Following New Cartesian Sign Convention, the image is formed at v = _____ and its height hI = ______ .
T he correct answer is -90 cm; -6.0 cm.Concept:Spherical mirror:A spherical mirror is a mirror that has the shape of a piece cut out of a spherical surface.There are two types of spherical mirrors: concave, and convex. Mirror formula:\(\frac{1}{f} = \frac{1}{v} + \frac{1}{u}\), where f = focal length, v = image distance and u = object distance.Magnification: m = \(\frac{Hi}{Ho} = \frac{-v}{u}\) , where Hi = height of image, Ho = height of object, v = image distance, and u = object distance.Concave mirror: It is part of a whole spherical mirror that reflects light from the hollow part.It is a converging mirror because it converges the incident rays at a point.Explanation:Given, u = -45 cm f = -30 cm h = 3 cm \(\frac{1}{f} = \frac{1}{v} + \frac{1}{u}\)\(\frac{1}{-30} = \frac{1}{v} + \frac{1}{-45}\)\(\frac{1}{-30} = \frac{1}{v} - \frac{1}{45}\)\(\frac{1}{v} = \frac{1}{-30} + \frac{1}{45} \)\(\frac{1}{v} = \frac{-3 + 2}{90} \)\(\frac{1}{v} = \frac{-1}{90} \)v = -90 cmm = \(\frac{Hi}{Ho} = \frac{-v}{u}\) = \(\frac{Hi}{3} = \frac{-(-90)}{-45}\) Hi = -2 À” 3 = -6 cmFollowing New Cartesian Sign Convention, the image is formed at v = -90 cm and its height HI = -6 cm. Additional InformationConvex mirror: It is part of a whole spherical mirror that reflects light from the bulged-out part.It diverges the incident rays.
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