Advertisements
Advertisements
Question

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.
Advertisements
Solution
i. Compound microscope
ii. Scientifically and technically correct figure.
(Object, Objective lens, Eye piece, Image)
iii. Magnification is obtained by the combined effect of two
lenses. The magnification occurs in two stages. The image formed by the first lens acts as the object for the second lens. Clear image can be obtained by adjusting the distance between two lenses.
iv. To study small sized objects like blood cells, animal and plant
cells, bacteria.
v. Any relevant remedy (For example, Selection of lens with
appropriate focal length)
APPEARS IN
RELATED QUESTIONS
An object is placed at a distance of 15 cm from a convex lens of focal length 20 cm. List four characteristics (nature, position, etc.) of the image formed by the lens.
If an object is placed at the focus of a convex lens, where is the image formed?
Where should an object be placed in order to use a convex lens as a magnifying glass?
Fill in the following blank with suitable word:
The image in a convex lens depends upon the distance of the ........... from the lens.
A convex lens of focal length 8 cm forms a real image of the same size as the object. The distance between object and its image will be:
(a) 8 cm
(b) 16 cm
(c) 24 cm
(d) 32 cm
Describe the nature of image formed when an object is placed at a distance of 30 cm from a convex lens of focal length 15 cm.
Find the nature, position and magnification of the images formed by a convex lens of focal length 0.20 m if the object is placed at a distance of:
0.15 m
A convex lens of focal length 15 cm produces a magnification of +4. The object is placed:
(a) at a distance of 15 cm
(b) between 15 cm and 30 cm
(c) at less than 15 cm
(d) beyond 30 cm
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?
Study the diagram given below.

- Name the lens LL’.
- What are the points O and O’ called?
- Complete the diagram to form the image of the object AB.
- State the three characteristics of the image.
- Name a device in which this action of lens is used.
Study the diagram below.

what are the points O, O’ called?
A converging lens forms the image of an object placed in front of it, beyond 2F2 of the lens. Draw a ray diagram to show the formation of the image.
The given below figure shows an object OA and its image IB formed by a lens
. 
draw suitable rays to locate the lens and its focus.
When you focus the image of a distant flag, whose shape is given below, on a screen using a convex lens, the shape of the image as it appears on the screen is
(A)
(B)
(C)
(D)
To find the image distance for varying object distances in case of a convex lens of focal length 15 cm, a student obtains on a screen a sharp image of a bright object by placing it at 20 cm distance from the lens. After that he gradually moves the object away from the lens and each time focuses the image on the screen.
(a) In which direction-towards or away from the lens does he move the screen to focus the object?
(b) How does the size of image change?
(c) Approximately at what distance does he obtain the image of magnification –1?
(d) How does the intensity of image change as the object moves farther and farther away from the lens?
State two applications of a convex lens.
What is the difference between a double convex and a bi-convex lens?
What happens to the image formed by a convex lens if its lower part is blackened?
Define the terms principal foci and focal lengths as applied to a convex lens, and show them with the help of proper diagrams.
