WAEC - Physics (2008 - No. 25)
The distance between a concave mirror and an object placed in front of it is 1.0m. If the raduis of curvature of the mirror is 4.0m, the image formed will be
2.00m behind the mirror
2.00m in front of the mirror
1.25m in front of the mirror
1.25m behind the mirror
Explication
The focal length of a concave mirror is negative
f = -2m
\(\frac{1}{f} = \frac{1}{v} + \frac{1}{u}\)
\(\frac{1}{-2} = \frac{1}{v} - \frac{1}{1}\)
\(\frac{1}{v} = \frac{1}{-2} + \frac{1}{1}\)
\(\frac{1}{v} = \frac{1}{2}\)
v = 2m
The image distance is 2.0 m in front of the mirror