Home
Class 11
PHYSICS
The real image produced by a convex lens...

The real image produced by a convex lens is magnified 4 times. What is the focal power of the lens, if the distance between the object and the image is 50 cm ?

A

6.5 D

B

8.5 D

C

10.5 D

D

12.5 D

Text Solution

Verified by Experts

The correct Answer is:
D
Given : `(v)/(u)=4 therefore v=4u and u+v=50 cm`
`therefore 4u+u=50 therefore u=10 cm and v=40 cm `
For the convex lens, `(1)/(v)-(1)/(u)=(1)/(f)` and u is negative.
`therefore (1)/(40)+(1)/(10)=(1)/(f) therefore (5)/(40)=(1)/(f) therefore f=8 cm`
`therefore` Focal power `=(1)/(f)` where f is in metre or `P=(100)/(f)`
`therefore P=(100)/(8)=12.5D`
Promotional Banner

Topper's Solved these Questions

  • RAY OPTICS (MIRRORS, LENSES AND OPTICAL INSTRUMENTS)

    MARVEL PUBLICATION|Exercise TEST YOUR GRASP|10 Videos

  • MEASUREMENTS

    MARVEL PUBLICATION|Exercise TEST YOUR GRASP|10 Videos

  • REFRACTION OF LIGHT

    MARVEL PUBLICATION|Exercise Test Your Grasp|10 Videos

Similar Questions

Explore conceptually related problems

A convex lens of focal length f produces a real image 3 times as that of size of the object, the distance between the object and the lens is

A convex lens produces a real image m times the size of the object. What will be the distance of the object from the lens ?

In a convex lens of focal length F, the minimum distance between an object and its real image mus be -

When a convex lens produces a real image of an object, the minimum distance between the object and image is equal to

A convex lens forms an image of an object on a screen ,The height of the image is 9cm The lens is now disiplaced between the object on the screen.the height of this image is 4cm .the distance between the object and the screen is 90cm

A convex lens forms a real and inverted image of a pencil at a distance of 40 cm from the lens. The image formed is of the same size as the object Find the focal length and power of the lens. At what distance is the : object placed from the lens?

A convex lens of focal length 8 cm forms a real image of the same size as the object. The distance between object and its image will be:

An object 25 cm high is placed in front of a convex lens of focal length 30 cm . If the height of image formed is 50 cm , find the distance between the object and the image (real and virtual)?