Q22 of 25 Page 10

A spherical mirror produces an image of magnification -1 on a screen placed at a distance of 50 cm from the mirror.(a) Write the type of mirror.(b) Find the distance of the image from the object.(c) What is the focal length of the mirror?(d) Draw the ray diagram to show the image formation in this case. ( CBSE 2014)

Given: magnification, m = -1

Image distance, v =50 cm


Since magnification is negative, it means that the image formed is real and inverted.


So, v = -50 cm


magnification is given by,




Therefore, u =-50 cm


(a) As image formation is on the screen and is a real image. Therefore, the mirror will be concave mirror.


(b) The distance of the image from the object will be -50 cm.


(c) Applying the lens formula:






so, f= -25 cm


(d) The ray diagram will be as follows:


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