The focal length of a concave mirror is f=20 cm. It is directed towards the sun and the sun makes an angle= 1° at the pole of the mirror. What is the size of the image of the sun?
1/u +1/v =1/f .....(i) ,magnification= v/u= l2/l1 where l1 =size of the sun,l2 =size of image of the sun.
The Attempt at a Solution
Here,u=∞(as the light comes from a very large distance),so from (i),v= f =20 cm.So v/u= 20/∞ =0=l2 /l1,from that, l2=0 or l1=∞.But which is right?Also I can't make a relation with the given angle.This is all what I have done.Please point out the mistake in my approach and also give hints to carry it out.