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Question
_______ times larger images can be obtained by using a simple microscope.
Options
5
10
20
60
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Solution
20 times larger images can be obtained by using a simple microscope.
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RELATED QUESTIONS
(a) Draw a ray diagram to show the formation of an image by a convex lens when an object is placed in front of the lens between its optical centre and principal focus.
(b) In the above ray diagram, mark the object distance (u) and the image distance (v) with their proper signs (+ve or –ve as per the new Cartesian sign convention) and state how these distances are related to the focal length (f) of the convex lens in this case.
(c) Find the power of a convex lens which forms a real and inverted image of magnification –1 of an object placed at a distance of 20 cm from its optical centre.
(a) Draw a ray diagram to show the formation of image by a concave lens when an object is placed in front of it.
(b) In the above diagram mark the object distance (u) and the image distance (v) with their proper signs (+ve or –ve as per the new Cartesian sign convention) and state how these distances are related to the focal length (f) of the concave lens in the case.
(c) Find the nature and power of a lens which forms a real and inverted image of magnification –1 at a distance of 40 cm from the optical centre.
"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.
A 1 cm high object is placed at a distance of 2f from a convex lens. What is the height of the image formed?
Explain with the help of a diagram, why the convex lens is also called a converging lens.
In order to obtain a real image twice the size of the object with a convex lens of focal length 15 cm, the object distance should be:
(a) more than 5 cm but less than 10 cm
(b) more than 10 cm but less than 15 cm
(c) more than 15 cm but less than 30 cm
(d) more than 30 cm but less than 60 cm
A convex lens of focal length 6 cm is held 4 cm from a newspaper which has print 0.5 cm high. By calculation, determine the size and nature of the image produced.
An object 3 cm high is placed 24 cm away from a convex lens of focal length 8 cm. Find by calculations, the position, height and nature of the image.
If the object is moved to a point only 3 cm away from the lens, what is the new position, height and nature 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.
What is the focal length of this lens?
The focal lengths of four convex lenses P, Q, R and S are 20 cm, 15 cm, 5 cm and 10 cm, respectively. The lens having greatest power is :
(a) P
(b) Q
(c) R
(d) S
Distinguish between:
Concave lens and Convex lens
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 pin 2 cm long is placed 12 cm away from a convex lens at right angles to the principal axis. If the focal length of the lens is 20 cm, by scale drawing find the size of the image and its magnification.
How will you decide whether a given piece of glass is a concave lens, convex lens, or a plane glass plate?
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.
State the position of object, position of image, nature of image when: Convex lens is used as objective lens of astronomical telescope.
State the nature and position of the object on the principal axis to obtain a virtual and magnified image.
Find the odd one out and give its explanation.
Differentiate convex lens and concave lens.
