Define the principal focus of a concave mirror?
Light rays that are parallel to the principal axis of a concave mirror converge at a specific point on its principal axis after reflecting from the mirror. This point is known as the principal focus of the concave mirror.
State the type of mirror preferred as (i) rear view mirror in vehicles, (i0 shaving mirror. Justify your answer giving two reasons in each case.[Delhi] ?
Distinguish between a real and a virtual image of an object. What type of image is formed (i) by a plane mirror, (ii) on a cinema screen? [Foreign]
An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed, so that a sharp focused image can be obtained? Find the size and the nature of the image.
A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object be placed so that it forms an image at 15 cm from the lens? Also calculate the size of the image formed. [Delhi]
A convex lens has a focal length of 10 cm. At what distance from the lens should the object be placed so that it forms a real and inverted image 20 cm away from the lens? What would be the size of the image formed if the object is 2 cm high? With the help of a ray diagram show the formation of the image by the lens in this case. [All India (C)]
The refractive index of glass is 1.50 and the speed of light in air is 3 x 108 ms-1. Calculate the speed of light in glass. [Foreign]
Name the type of mirror used in the following situations.
(a) Headlights ofa car
(b) Side/rear-view mirror of a vehicle
(c) Solar furnace
Support your answer with reason.
Draw a ray diagram and also state the position, the relative size and the nature of image formed by a concave mirror when the object is placed at the centre of curvature of the mirror. [Delhi]
A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal or away from the normal? Why?
Draw the ray diagram in each case to show the position and nature of the image formed when the object is placed:
(i) at the centre of curvature of a concave mirror
(ii) between the pole P and focus F of a concave mirror
(iii) in front of a convex mirror
(iv) at 2F of a convex lens
(v) in front of a concave lens
How far should an object be placed from a .convex lens of focal length 20 cm to obtain its image at a distance of 30 cm from the lens? What will be the height of the image if the object is 6 cm tall? [All India]
A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the lens if the image is equal to the size of the object? Also find the power of the lens.
A doctor has prescribed a corrective lens of power +1.5 D. find the focal length of the lens. Is the prescribed lens diverging or converging?
What is the nature of the image formed by a concave mirror if the magnification produced by the mirror is +3? [Delhi]
An object 5cm in length is held 25cm away from a converging lens of focal length 10 cm. Draw a ray diagram and find the position, size and the nature of the image formed.
Redraw the diagram given below in your answer book and show the direction of the light ray after reflection from the mirror. [Delhi (C)]
Redraw the diagram given below in your answer book and show the direction of the light ray after refraction from the lens. [Delhi, All India(C)]
At what distance should an object be placed from a convex lens of focal length 18 cm to obtain an image at 24 cm from it on the other side. What will be the magnification produced in this case? [Delhi]
An object 5.0 cm in length Is placedat a distanc, of 20 cm in front of a convex mirror of radius of curvature 30 cm. Find the position of the image nature and size.
The refractive indices of four media A, B, C and D are given in the following table:
If light, travels from one medium to another, in which case the change in speed will be (i) minimum, (ii) maximum? [Delhi(C)]
An object 2 cm high is placed at a distance of 64 cm from a white screen. On placing a convex lens at a distance of 32 cm from the object it is found that a distinct image of the object is formed on the screen. What is the focal length of the convex lens and size of the image formed on the screen? Draw a ray diagram to show the formation of the image in this position of the object with respect to the lens. [Delhi(C)]
Redraw the diagram given below in your answer book and show the direction of the light ray after refraction from the lens. [All India (C)]
How should a ray of light be incident on a rectangular glass slab so that it comes out from the opposite side of the slab without being displaced? [Foreign]
The image of an object placed at 60 cm in front of a lens is obtained on a screen at a distance of 120 cm from it. Find the focal length of the lens. What would be the height of the image if the object is 5 cm high? [Foreign]
Draw the following diagram in your answer book and show the formation of image of the object AB with the help of suitable rays. [All India]
The refractive index of water is 1.33 and the speed of light in air is 3 x 108 ms-1. Calculate the speed of light in water. [Foreign]
An object is placed between infinity and the pole of a convex mirror. Draw a ray diagram and also state the position, the relative size and the nature of the image formed. [All India]
(a) What is meant by ‘power of a lens’?
(b) State and define the S.I. unit of power of a lens.
(c) A convex lens of focal length 25 cm and a concave lens of focal length 10 cm are placed in close contact with each other. Calculate the lens power of this combination. [All India]
You are given kerosene, turpentine and water. In which of these does the light travel fastest?
(a) “The refractive index of diamond is 2.42”. What is the meaning of this statement?
(b) Name a liquid whose mass density is less than that of water but it is optically denser than water. [Delhi]
Draw the ray diagram and also state the position, relative size and nature of the image formed by a concave mirror when the object is placed between its centre of curvature, C and focus, F. [Foreign]
If a light ray IM is incident on the surface AB as shown, identify the correct emergent ray. [Delhi (C)]
“The refractive index of diamond is 2.42”. What is the meaning of this statement in relation to speed of light? [Delhi]
Redraw the diagram given below in your answer book and show the direction of the light ray after reflection from the mirror. [Delhi (C)]
A ray of light travelling in air enters obliquely into water. Does the light ray bend towards or away from the normal ? Why? Draw a ray diagram to show the refraction of light in this situation. [Delhi]
An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens. [All India]
The outer surface of a hollow sphere of aluminium of radius 50 cm is to be used as a mirror. What will be the focal length of this mirror? Which type of spherical mirror will it provide? [Delhi]
Explain with the help of a diagram, why a pencil partly immersed in water appears to be bent at the water surface. [Delhi]
