Question

How fast should on object be placed from the pole of convering mirror of focal length 30pm to forms red image of the size enter ally 1/4the size of the object

Answer 1

ANS: we have a false balance which have equal arms so falseness is due to weight of the pan and balance is based on principle of torque.

let first pan have x weight more than other so,  

x+w1=W.........(1) W + x=w2.......(2)  

from (1) and (2)

W= (w1+ w2)/2