A lens when placed on a plane mirror then object needle and its image coincide at 15 cm . The focal length of the lens is
A
15 cm 
B
30 cm
C
20 cm
D
∞ ∞
Text Solution
Verified by ExpertsThe correct answer is:
A
When the object is placed at focus the rays are parallel. The mirror placed normal sends them back. Hence image is formed at the object itself as illustrated in figure.
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 convex lens of power + 6 D is placed in contact with a concave lens of power – 4 D . What is the …
A lens of focal power 0.5 D is
A lens which has focal length of 4 cm and refractive index of 1.4 is immersed in a liquid of refrac…
A convex lens has 9 cm focal length and a concave lens has – 18 cm focal length. The focal length o…
A double convex thin lens made of glass of refractive index 1.6 has radii of curvature 15 cm each. …
A candle placed 25 cm from a lens, forms an image on a screen placed 75 cm on the other end of the …