The image of an object placed 20 cm in front of a concave mirror of focal length 10 cm will be
A) virtual and inverted.
B) virtual and erect.
C) real and inverted.
D) real and erect.

Question

Quizplus · Accepted Answer

Using the mirror formula $\frac{1}{f}=\frac{1}{v}+\frac{1}{u}$, where $f$ is the focal length, $v$ is the image distance and $u$ is the object distance, we get:

$\frac{1}{f}=\frac{1}{v}+\frac{1}{u} \implies \frac{1}{10}=\frac{1}{v}+\frac{1}{20} \implies v=-20$ cm

Since the distance of the image is negative, it means that the image is formed behind the mirror. 
Also, since the object is placed beyond the focal length of the concave mirror, the image formed is real and inverted.

Therefore, the correct choice is C: real and inverted.

The Image of an Object Placed 20 Cm in Front