A body is located on a wall. Its image of equal size is to be obtained on a parallel wall with the help of a convex lens. The lens is placed at a distance d ahead of second wall, then the required focal length will be:
A
Only 
B
Only 
C
More than 
but less than 
but less than
D
Less than 
Text Solution
Verified by ExpertsThe correct answer is:
B
The lens formula can be written as
= 
.... (i)
Given v = d
For equal size image
| v | = | u | = d
By sign convention , u = – d
∴ 
= 
or f = 
Prepare Smarter with CGP Edu
Get practice questions, solutions, and test series in one place.
Write a Review
Share your experience with this question and solution.
Commentary
Send your comment, doubt, correction, or feedback to admin.
Similar Questions
Explore conceptually related problems
A double convex lens of glass of μ μ = 1.5 has radius of curvature of each of its surface is 0.2 m.…
A convex lens of focal length 25 cm and a concave lens of focal length 10 cm are joined together. T…
The focal lengths of convex lens for red and blue light are 100 cm and 96.8 cm respectively. The di…
The power of an achromatic convergent lens of two lenses is + 2 D . The power of convex lens is + 5…
A thin glass (refractive index 1.5) lens has optical power of in air. It's optical power in a liqu…
Dispersive power depends upon