When an object is placed 20cm from a concave mirror , a real image magnified three times is formed. Find:
(a) focal length of the mirror.
(b) where must the object be placed to give a virtual image three times the height of the object?
Magnification, m=-3 (Image is real)
Object distance, u=-20cm
Thus the image is located at a distance of 60cm in front of the mirror.
Now using the mirror formula,
1/(-60) + 1/(-20)=1/f
m=h2 /h1=- v/u=3
Using mirror formula,