Question

a shaving mirror is at 28 cm from the face of a person if the focal length of the shaving mirror is 80 cm then find the distance of image from the mirror and magnification of mirror vish​

Answer 1

Since it is a shaving mirror the type of mirror will be convex
u=-28 cm, f=80 cm, v=?
By mirror formula,
(1/f)=(1/u)+(1/v)
(1/80)=(1/-28)+(1/v)
(1/80)=(-1/28)+(1/v)
1/v=(1/80)+(1/28)
1/v=(7+20)/560
1/v=27/560
v=560/27
v=20.74 cm
Distance of image from the mirror=20.74 cm
Now,
Magnification of mirror(m)=(-v/u)
=(-560/27)/-28
=(-560/27)*(1/-28)
=20/27
=0.74