Question

calculate the focal length if the object is at infinite distance in case of concave mirror

Answer 1

Answer is 0
#hope u r satisfied from this answer

Answer 2

hello!
if object is at infinity than the object distance will be n and the image will be formed at focus, so the image distance will be equal to focal length
now,
1/f=1/v+1/u
1/f=1/f+1/n
taking lcm,
1/f=(n+f)/nf
cross multipling,
nf=nf+f^2
nf-nf=f^2
f^2=0
so,
f=0
hope it helps u!
thanks!^_^