State Two Main Differences Between a Convex and Concave Lens. - Physics

Distinguish Between
State two main differences between a convex and concave lens.


Convex lens Concave lens
1. A convex lens is thicker in the middle and thinner at its edges. 1. A concave lens is thicker at the edges and thinner in the middle.
2. A light beam converges on passing through a convex lens. 2. A light beam diverges on passing through a concave lens.
Concept: Convex Lens
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Chapter 2: Light - Exercise 2.2 i [Page 101]


Frank ICSE Class 10 Physics Part 2
Chapter 2 Light
Exercise 2.2 i | Q 2 | Page 101


To determine the approximate focal length of the given convex lens by focussing a distant object (say, a sign board), you try to focus the image of the object on a screen. The image you obtain on the screen is always

(a) erect and laterally inverted

(b) erect and diminished

(c) inverted and diminished

(d) virtual, inverted and diminished

One-half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations.

A student places a candle flame at a distance of about 60 cm from a convex lens of focal length 10 cm and focuses the image of the flame on a screen. After that he gradually moves the flame towards the lens and each time focuses the image on the screen.  

(a) In which direction-toward or away from the lens, does he move the screen to focus the image?
(b) How does the size of the image change?
(c) How does the intensity of the image change as the flame moves towards the lens?
(d) Approximately for what distance between the flame and the lens, the image formed on the screen is inverted and of the same size?

"A lens can form a magnified erect image as well as magnified inverted image of an object placed in front of it." State the nature of this lens and draw ray diagrams to justify the above statement. Mark the positions of O, F and 2F in the diagram.

When a ray of light enters from one medium to another having different optical densities it bends. Why does this phenomenon occur?

A lens forms an erect, magnified and virtual image of an object.

(i) Name the lens.
(ii) Draw a labelled ray diagram to show the image formation. 

Fill in the following blank with suitable word: 

The image in a convex lens depends upon the distance of the ........... from the lens.

Distinguish between a convex lens and concave lens. Which of the two is a converging lens : convex lens of concave lens?

An object is placed f and 2f of a convex lens. Which of the following statements correctly describes its image? 

(a) real, larger than the object
(b) erect, smaller than the object
(c) inverted, same size as object
(d) virtual, larger than the object

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

A ray of light after refraction through a convex lens emerges parallel to principal axis. (a) Draw a ray diagram to show it. (b) The incident ray passes through a point on the principal axis. Name the point

A convex lens forms an image of an object equal to the size of the object.Where is the object placed in front of the lens?

For the object placed between optical centre and focus of a convex lens, the image is:

An object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm. The distance of the object from the lens is 30 cm. Find (i) the position (ii) the magnification and (iii) the nature of the image formed.

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 F1 and F2 of symmetric convex lens experimentally then which conclusion is true.

Where should an object be placed in front of a convex lens to get a real image of the size of the object?

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.

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

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.

Answer the following question.
List four precautions which a student should observe while determining the focal length of a given convex lens by obtaining an image of a distant object on a screen. 

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

State the nature and position of the object on the principal axis to obtain a virtual and magnified image.

A concave mirror and convex lens are held in water. What changes, if any, do you expect in their focal length?

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 2F1 of a convex lens : Image at 2F2 : : Object at F1 : _______

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.

  1. Where is the above type of lens construction used?
  2. What type of image is formed by an objective lens?
  3. What happens instead of placing at Fo if the object is placed in between O and Fo?

Differentiate convex lens and concave lens.

  1. In which type of microscope do you find the lens arrangement as shown in the following diagram?
  2. 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

Distinguish between:

Concave lens and Convex Lens


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