###### Advertisements

###### Advertisements

Out of the two lenses one concave and the other convex state which is a convergent or a divergent type of a lens. Give a reason for your answer.

###### Advertisements

#### Solution

The convex lens is a convergent type of a lens since it converges the light rays to a point while the concave lens is a divergent type of lens since it spreads the light rays.

#### APPEARS IN

#### RELATED QUESTIONS

Study the given ray diagrams and select the correct statement from the following:

(A) Device X is a concave mirror and device Y is a convex lens, whose focal lengths are 20 cm and 25 cm respectively.

(B) Device X is a convex lens and device Y is a concave mirror, whose focal lengths are 10 cm and 25 cm respectively.

(C) Device X is a concave lens and device Y is a convex mirror, whose focal lengths are 20 cm and 25 cm respectively.

(D) Device X is a convex lens and device Y is a concave mirror, whose focal lengths are 20 cm and 25 cm respectively.

Complete the following table:

Instrument |
Number of ConvexLenses |
Use |

Simple Microscope | .............. | .............. |

Compound Microscope | .............. | .............. |

Telescope | .............. | .............. |

Fill in the following blank with suitable word:

Parallel rays of light are refracted by a convex lens to a point called the ........

An object is placed at a distance equal to 2*f* in front of a convex lens. Draw a labelled ray diagram to show the formation of image. State two characteristics of the image formed.

How could you find the focal length of a convex lens rapidly but approximately?

An object 4 cm high is placed at a distance of 10 cm from a convex lens of focal length 20 cm. Find the position, nature and size of the image.

A student did an experiment with a convex lens. He put an object at different distances 25 cm, 30 cm, 40 cm, 60 cm and 120 cm from the lens. In each case he measured the distance of the image from the lens. His results were 100 cm, 24 cm, 60 cm, 30 cm and 40 cm, respectively. Unfortunately his results are written in wrong order.

Rewrite the image distances in the correct order.

A student did an experiment with a convex lens. He put an object at different distances 25 cm, 30 cm, 40 cm, 60 cm and 120 cm from the lens. In each case he measured the distance of the image from the lens. His results were 100 cm, 24 cm, 60 cm, 30 cm and 40 cm, respectively. Unfortunately his results are written in wrong order.

What would be the image distance if the object distance was 90 cm?

Which causes more bending (or more refraction) of light rays passing through it : a convex lens of long focal length or a convex lens of short focal length?

What type of lens is used to correct

hypermetropia

Study the following diagram :

What are the points O and O’ called?

Where is the image formed?

Give two characteristic of the virtual image formed by a convex lens.

In the following cases, where must an object be placed in front of a convex lens so that the image formed is at infinity.

**Distinguish between: **

Concave lens and Convex lens

i. Which type of microscope has the arrangement of lenses shown in the adjoining figure?

ii. Label the figure correctly.

iii. Write the working of this microscope.

iv. Where does this microscope used?

v. Suggest a way to increase the efficiency of this microscope.

The image obtained while finding the focal length of convex lens is ....................

Observe the following figure and answer the questions.

a) Which optical instrument shows arrangement of lenses as shown in the figure?

b) Write in brief the working of this optical instrument.

c) How can we get different magnifications in this optical instrument?

d) Draw the figure again and labelled it properly

Yesh find out F_{1} and F_{2} of symmetric convex lens experimentally then which conclusion is true.

**Observe the following figure and complete the table:**

Points |
Answer |

(i) Position of the object | |

(ii) Position of the image | |

(iii) Size of the image | |

(iv) Nature of the image |

A lens always forms an image between the object and the lens.

state three characteristics of the image.

If an object is placed in front of a convex lens beyond 2F1, then what will be the position, relative size, and nature of an image which is formed? Explain with a ray diagram.

**Rewrite the following statement by selecting the correct option:**

What is lens?

How will you decide whether a given piece of glass is a concave lens, convex lens, or a plane glass plate?

State the position of object, position of image, nature of image when: Convex lens is used as objective lens of astronomical telescope.

State the position of object, position of image, nature of image when: Convex lens is used in observing biological specimens.

For a specific glass lens f = 0.5 m. This is the only information given to the student. Which type of lens is given to him and what is its power?

_______ times larger images can be obtained by using a simple microscope.

_______ is a combination of two convex lenses with small focal length.

Object at 2F_{1} of a convex lens : Image at 2F_{2} : : Object at F_{1} : _______

Simple microscope : Number of convex lens one : : compound microscope : _______

: Object near the lens : : ______ :

**Find the odd one out and give its explanation.**

**Find the odd one out and give its explanation.**

**Write the name.**

The lens used in simple microscope.

**Write scientific reason.**

Adults need bifocal lens spectacle.

**Observe the given figure and answer the following questions.**

- Where is the above type of lens construction used?
- What type of image is formed by an objective lens?
- What happens instead of placing at F
_{o}if the object is placed in between O and F_{o}?

Differentiate convex lens and concave lens.

Convex lens is also known as ______.

- In which type of microscope do you find the lens arrangement as shown in the following diagram?
- Write about the working and the use of this microscope.

Distinguish between Concave lens and Convex lens.

**Distinguish between:**

Concave lens and Convex Lens

Distinguish between Concave lens and Convex Lens.

**Distinguish between:**

Concave lens and Convex Lens