An object is placed 40 cm in front of a convex mirror of radius of curvature 20 cm. The image:
Answer & explanation
Correct answer: option 4
According to new Cartesian sign conventions,
u = -40 cm, R = +20 cm
f = $\frac{R}{2}$ = +10 cm
According to mirror formula
$\frac{1}{u}+\frac{1}{v}=\frac{1}{f}$ ∴ $\frac{1}{-40}+\frac{1}{v}=\frac{1}{10}$
$\frac{1}{v}=\frac{1}{10}+\frac{1}{40}=\frac{1}{8}$ or v = 8 cm
The image is formed at 8 cm behind the mirror. It is a virtual image.