An object is placed 25cm in front of a convex mirror has its image formed 5cm behind the mirror. what is the focal length of the convex mirror
- 8.20cm
-
6.25cm
- 5.60cm
- 4.50cm
The correct answer is: B
Explanation
Object distance (u) = -25 cm (negative because the object is in front of the mirror)
Image distance (v) = +5 cm (positive because the image is behind the convex mirror)
Using \(\frac{1}{f}\) = \(\frac{1}{u}\) + \(\frac{1}{v}\)
\(\frac{1}{f}\) = \(\frac{1}{-25}\) + \(\frac{1}{5}\)
f = \(\frac{25}{4}\) = 6.250cm.
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