English
Maharashtra State BoardSSC (English Medium) 10th Standard

Give a scientific reason. Simple microscope is used for watch repairs.

Advertisements
Advertisements

Question

Give a scientific reason.

Simple microscope is used for watch repairs.

Give Reasons
Advertisements

Solution 1

  1. When an object is put inside the focal length of a magnifying glass or simple microscope (convex lens), the larger and erect image appears on the same side of the lens as the object.
  2. By altering the distance between the object and the lens, the image can be obtained at the shortest distance of distinct vision. Thus, a watch repairer may see the minute parts of a watch more clearly with the use of a magnifying glass (a rudimentary microscope) than with the naked eye, and without putting any strain on the eye. As a result, watch repairers utilise a magnifying glass (a basic microscope) to repair the timepieces.
shaalaa.com

Solution 2

  1. In a simple microscope, a convex lens with a small focal length is used.
  2. It produces a virtual, erect, and bigger image of an object.
  3. We can get a 20 times larger image of an object using a simple microscope.

Hence, watch repairers use a simple microscope while repairing watches.

shaalaa.com
  Is there an error in this question or solution?
Chapter 7: Lenses - Exercises [Page 92]

RELATED QUESTIONS

A converging lens has focal length of 12 cm. Calculate at what distance the object should be placed from the lens so that it forms an image at 48 cm on the other side of the lens.


A divergent lens of focal length 30 cm forms the image of an object of size 6 cm on the same side as the object at a distance of 15 cm from its optical centre. Use lens formula to determine the distance of the object from the lens and the size of the image formed.


An object of height 4 cm is placed at a distance of 20 cm from a concave lens of focal length 10 cm. Use lens formula to determine the position of the image formed.


The image of a candle flame placed at a distance of 30 cm from a spherical lens is formed on a screen placed on the other side of the lens at a distance of 60 cm from the optical centre of the lens. Identify the type of lens and calculate its focal length. If the height of the flame is 3 cm, find the height of its image.


A student wants to project the image of a candle flame on a screen 60 cm in front of a mirror by keeping the flame at a distance of 15 cm from its pole.

(a) Write the type of mirror he should use.

(b) Find the linear magnification of the image produced.

(c) What is the distance between the object and its image?

(d) Draw a ray diagram to show the image formation in this case.


At what distance from a concave lens of focal length 20 cm, should a 6 cm tall object be placed so that it forms an image at 15 cm from the lens ? Also determine the size of the image formed.


A spherical mirror produces an image of magnification -1 on a screen placed at a distance of 50 cm from the mirror.

(a) Write the type of mirror.

(b) Find the distance of the image from the object.

(c) What is the focal length of the mirror?

(d) Draw the ray diagram to show the image formation in this case.


What is the difference between a real image and a virtual image? Give one example of each type of image


Linear magnification produced by a concave mirror may be:

(a) less than 1 or equal to 1
(b) more than 1 or equal than 1
(c) less than 1, more than 1 or equal to 1
(d) less than 1 or more than 1


In order to obtain a magnification of −2 (minus 2) with a concave mirror, the object should be placed:

(a) between pole and focus
(b) between focus and centre of curvature
(c) at the centre of curvature
(d) beyond the centre of curvature


If a magnification of, −1 (minus one) is to be obtained by using a converging mirror, then the object has to be placed:

(a) between pole and focus
(b) at the centre of curvature
(c) beyond the centre of curvature
(d) at infinity


In order to obtain a magnification of, −0.6 (minus 0.6) with a concave mirror, the object must be placed:

(a) at the focus
(b) between pole and focus
(c) between focus and centre of curvature
(d) beyond the centre of curvature


Linear magnification (m) produced by a rear view mirror fitted in vehicles:

(a) is equal to one
(b) is less than one
(c) is more than one
(d) can be more less than one depending on the position of object


Explain what is meant by a virtual, magnified image. 


 Draw a ray diagram to show the formation of a virtual magnified image of an object by a convex lens. In your diagram, the position of object and image with respect to the principal focus should be shown clearly. 


The lens A produces a magnification of, − 0.6 whereas lens B produces a magnification of + 0.6.  

 What is the nature of lens A?


The lens A produces a magnification of, − 0.6 whereas lens B produces a magnification of + 0.6. 

What is the nature of lens B


A student wants to project the image of a candle flame on a screen 80 cm in front of a mirror by keeping the candle flame at a distance of 20 cm from its pole.

  1. Which type of mirror should the student use?
  2. Find the magnification of the image produced.
  3. Find the distance between the object and its image.
  4. Draw a ray diagram to show the image formation in this case and mark the distance between the object and its image.

An object of height 6 cm is placed perpendicular to the principal axis of a concave lens of focal length 5 cm. Use lens formula to determine the position, size and nature of the image if the distance of the object from the lens is 10 cm. 


The image of a candle flame placed at a distance 36 cm from a spherical lens is formed on a screen placed at a distance of 72 cm from the lens. Identify the type of lens and calculate its focal length. If the height of the flame is 2.5 cm, find the height of its image.


At what distance should an object be placed from a lens of focal length 25 cm to obtain its image on a screen placed on the other side at a distance of 50 cm from the lens? What will be the magnification produced in this case?


Solve the following example.
5 cm high object is placed at a distance of 25 cm from a converging lens of focal length of 10 cm. Determine the position, size and type of the image.


At which position will you keep an object in front of convex lens to get a real image smaller than the object? Draw a figure.


Find the position and magnification of the image of an object placed at distance of 8.0 cm in front of a convex lens of focal length 10.0 cm. Is the image erect or inverted?


The lens of the eye is flattened when looking at nearby objects.


An object is placed vertically at a distance of 20 cm from a convex lens. If the height of the object is 5 cm and the focal length of the lens is 10 cm, what will be the position, size and nature of the image? How much bigger as compared to the object?


Ravi kept a book at a distance of 10 cm from the eyes of his friend Hari. Hari is not able to read anything written in the book. Give reasons for this?


The focal length of a concave lens is 20 cm. At what distance from the lens should a 5 cm tall object be placed so that its image is formed at a distance of 15 cm from the lens? Also calculate the size of the image formed.


The magnification by a lens is -3. Name the lens and state how are u and v related?


What information about the nature of image is erect or inverted, do you get from the sign of magnification + or -?


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×