An object is placed 10 cm in front of a concave mirror of focal length 30 cm. The image will be formed
A) 20 cm in front of the mirror.
B) 20 cm behind the mirror.
C) 15 cm in front of the mirror.
D) 15 cm behind the mirror.
E) 0.05 cm behind the mirror.

Question

Quizplus · Accepted Answer

Using the mirror equation: 
1/f = 1/p + 1/q 
where f is the focal length, p is the distance of the object from the mirror, and q is the distance of the image from the mirror. 
Plugging in the given values: 
1/30 = 1/10 + 1/q 
Solving for q: 
q = -15 cm (negative sign indicates that the image is formed behind the mirror) 
Therefore, the image is formed 15 cm behind the mirror.

An Object Is Placed 10 Cm in Front of a Concave