Question Detail
Question
A concave mirror of radius curvature 20 cm has an object placed 20 cm from it. Determine the distance of the image formed from the mirror.
Correct Answer
Option B is the correct answer.
Detailed Explanation
For a concave mirror, the focal length (f) is half the radius of curvature (R): f = R/2.Given R = 20 cm, so f = 20 cm / 2 = 10 cm.The object is placed at a distance u = 20 cm from the mirror.Using the mirror formula: 1/f = 1/u + 1/v, where v is the image distance.1/10 = 1/20 + 1/v1/v = 1/10 - 1/201/v = 2/20 - 1/201/v = 1/20v = 20 cm.When an object is placed at the center of curvature (which is 2f or R) of a concave mirror, the image is formed at the center of curvature as well.
Hint
Recall the mirror formula and the relationship between focal length and radius of curvature for a spherical mirror.