Answers

2014-11-30T07:46:14+05:30
If it is concave mirror then,f=-20cm
As specific denotion
h2=1/3 h1
h2/h1=1/3=m
as we know that m=-v/u=1/3
v=-1/3u
applied mirror formula
1/f=1/v+1/u
1/-20=-3u/1+1/u
-1/20=-3u^2+1 whole divided by u
cross multiply
-u=-60u^2+20
60u^2-u-20=0
solve quartic equation
u=71/120,u=69/120
u=0.59 and u=0.57
0