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A 3cm tall object is placed at a distance of 18cm in front of a concave mirror of focal length 12cm.find the position,nature and size of the image formed. |
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Answer» Explanation: given, HEIGHT of OBJECT,h = 3 cm object distance,u = -18 cm (since concave mirror) focal length,f = -12 cm now, using the formula 1/u + 1/v = 1/f 1/-18 + 1/ v = 1/-12 1/v= 1/18+1/-12 1/v= (2+3)/36 1/v= 5/36 v= 36/5 v= 7.2 hence, image distance is 7.2 cm and it will form back side of the concave mirror now magnification m= h'/h or m=-v/u then we have h'/h= -v/u h'/3=-(36/5)/(-18) = 36/5 * 1/18 = 2/5 * 1 5h'= 6 h' = 6/5 h' = 1.2cm hence we can CONCLUDE that the image will be 1.2 cm bigger than the object |
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