Advertisements
Advertisements
Question
The lens of the eye is flattened when looking at nearby objects.
Options
Right
Wrong
Advertisements
Solution
The lens of the eye is flattened when looking at nearby objects- Wrong
APPEARS IN
RELATED QUESTIONS
A student is using a convex lens of focal length 10 cm to study the image formation by a convex lens for the various positions of the object. In one of his observations, he may observe that when the object is placed at a distance of 20 cm from the lens, its image is formed at (select the correct option)
(A) 20 cm on the other side of the lens and is of the same size, real and erect.
(B) 40 cm on the other side of the lens and is magnified, real and inverted.
(C) 20 cm on the other side of the lens and is of the same size, real and inverted.
(D) 20 cm on the other side of the lens and is of the same size, virtual and erect.
The image formed by a spherical mirror is real, inverted and is of magnification −2. If the image is at a distance of 30 cm from the mirror, where is the object placed? Find the focal length of the mirror. List two characteristics of the image formed if the object is moved 10 cm towards the mirror.
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.
An object is held 20 cm away from a converging lens of focal length 10 cm. Find the position of the image formed.
The image seen in a plane mirror cannot be formed on a screen. What name is given to this type of image?
When an object is placed at a distance of 50 cm from a concave spherical mirror, the magnification produced is, `-1/2`. Where should the object be placed to get a magnification of, `-1/5`?
An object is placed (a) 20 cm, (b) 4 cm, in front of a concave mirror of focal length 12 cm. Find the nature and position of the image formed in each case.
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
Draw a diagram to show how a converging lens held close to the eye acts as a magnifying glass. Why is it usual to choose a lens of short focal length for this purpose rather than one of long focal length?
Explain what is meant by a virtual, magnified image.
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?
Draw a ray diagram to show how a converging lens is used as a magnifying glass to observe a small object. Mark on your diagram the foci of the lens and the position of the eye.
The image of a candle flame placed at a distance 30 cm from a spherical lens is formed on a screen placed at a distance of 60 cm from the lens. Identify the type of lens and calculate its focal length. If the height of the flame is 2.4 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?
At which position will you keep an object in front of a convex lens so as to get a real image of the same size as the object? Draw a figure.
Give a scientific reason.
Simple microscope is used for watch repairs.
Magnification of a convex lens is ______.
The image of a candle flame formed by a lens is obtained on a screen placed on the other side of the lens. If the image is three times the size of the flame and the distance between lens and image is 80 cm, at what distance should the candle be placed from the lens? What is the nature of the image at a distance of 80 cm and the lens?
A lens of focal length 5 cm is being used by Debashree in the laboratory as a magnifying glass. Her least distance of distinct vision is 25 cm.
- What is the magnification obtained by using the glass?
- She keeps a book at a distance 10 cm from her eyes and tries to read. She is unable to read. What is the reason for this?
The magnification produced when an object is placed at a distance of 20 cm from a spherical mirror is +1/2. Where should the object be placed to reduce the magnification to +1/3.
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.
In a reading glass what is the position of the object with respect to the convex lens used?
Write an expression for magnification for a lens, explaining the meaning of the symbols used.
What information about the nature of image is erect or inverted, do you get from the sign of magnification + or -?
