When an Object is Placed 10 Cm in Front of Lens A, the Image is Real, Inverted, Magnified and Formed at a Great Distance. When the Same Object is Placed 10 Cm in Front of Lens B, The Image Formed is Real, Inverted and Same Size as the Object. What is the Nature of Lens B? - Science


When an object is placed 10 cm in front of lens A, the image is real, inverted, magnified and formed at a great distance. When the same object is placed 10 cm in front of lens B, the image formed is real, inverted and same size as the object. 

 What is the nature of lens B? 



 Lens B is a converging (convex) lens as only a converging lens forms a real image.

Concept: Concave Lens
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Chapter 5: Refraction of Light - Exercise 5 [Page 253]


Lakhmir Singh Class 10 Physics (Science)
Chapter 5 Refraction of Light
Exercise 5 | Q 23.4 | Page 253


Explain with the help of a diagram, why the concave lens is also called a diverging lens.

 How would you alter the above diagram to show how a converging lens can produce a beam of parallel rays of light. 

A converging lens of focal length 5 cm is placed at a distance of 20 cm from a screen. How far from the lens should an object be placed so as to form its real image on the screen?


Which type of lenses are: 

thinner in the middle than at the edges?

A ray of light is going towards the focus of a concave lens. draw a ray diagram to show the path of this ray of light after refraction through the lens.

What type of image is always made by a concave lens?

An object lies at a distance of 2f from a concave lens of focal length f. Draw a ray-diagram to illustrate the image formation.

What is the difference between the two images formed above? 

A concave lens has focal length 15 cm. At what distance should the object from the lens be placed so that it forms an image at 10 cm from the lens? Also find the magnification produced by the lens. 

Show by a diagram, the refraction of two light rays incident parallel to the principal axis on a concave lens by treating it as a combination of a glass block and two triangular glass prisms.

Define the term principal foci of a concave lens and show them with the help of proper diagrams.


Draw a diagram to represent the second focus of a concave lens.

Study the following diagram :

Name the lens LL’

The following diagram in given below shows an object OA and its virtual image IB formed by a lens.

State the changes in the position, size and nature of the image of an object when brought from infinity up to a concave lens. Illustrate your answer by drawing ray diagrams.

State whether the following statement are ‘true’ or ‘false’ by writing T/F against them.

A concave lens forms a magnified or diminished image depending on the distance of object from it.

State two applications  a concave lens .

Explain the working of an astronomical telescope using refraction of light.


A student obtained clear image of window grills on the screen. But the teacher told him to get the image of a tree far away, instead of window. To get a clear image,  the lens must be ............................

Write the SI unit of focal length of a concave lens.

Choose the correct alternative and rewrite the following: 

Inside water, an air bubble behaves ....................

Copy the following figure and complete it to show the formation of the image of the object AB. Name the lens used in the figure.

Define the principal focus of a concave lens.

Convex lens : converging : : concave lens : _______

Convex magnifying glass is called divergent magnifying glass and concave magnifying glass is called converging magnifying glass.

Distinguish between Concave lens and Convex Lens.

Distinguish between:

Concave Lens and Convex Lens


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