Question

A concave mirror forms a real image of an object magnified 2 times. The distance between the object and the image is 20cm . What is the radius of curvature ?

Answer 1

ANSWER

u=−30cm and magnification m=(−v/u)=−3 so v=(3u)

image is real so m should be negative v should be negative so v=−90cm

putting the above values of v and u in the Mirror equation,

f

1

​  

=  

u

1

​  

+  

v

1

​  

 

we get focal length f=−22.5cm and image position v=−90cm