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?
The light ray bends towards the normal. When a ray of light travels from an optically rarer medium to an optically denser medium, it gets bent towards the normal. Since water is optically denser than air, a ray of light travelling from air into the water will bend towards the normal.
To construct a ray diagram, we use two light rays which are so chosen that it is easy to know their directions after reflection from the mirror. List these two rays and state the path of these rays after reflection. Use these rays to locate the image of an object placed between centre of curvature and focus of a concave mirror. [All India]
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]
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] ?
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
A concave mirror produces three times magnified (enlarged) real image of object placed at 10 cm in front of it. Where is the image located?
Define the focus of a concave mirror. If the radius of curvature of a convex mirror is 30 cm, what would be its focal length? [Foreign]
Redraw the diagram given below in your answer book and show the direction of the light ray after reflection from the mirror. [Delhi (C)]
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.
One half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations.
Define ‘refractive index of a transparent medium.’ What is its unit? Which has a higher refractive index, glass or water? [Delhi]
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]
What is the nature of the image formed by a concave mirror if the magnification produced by the mirror is +3? [Delhi]
“The refractive index of diamond is 2.42”. What is the meaning of this statement in relation to speed of light? [Delhi]
Between which two points of a concave mirror should an object be placed to obtain a magnification of -3? [Delhi]
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.
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) “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]
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]
List four properties of the image formed by a concave mirror, when object is placed between focus and pole of the mirror. [Delhi]
In an experiment with a rectangular glass slab, a student observed that a ray of light incident at an angle of 55 ° with the normal on one face of the slab, after refraction strikes the opposite face of the slab before emerging out into air making an angle of 40 ° with the normal. Draw a labelled diagram to show the path of this ray. What value would you assign to the angle of refraction and angle of emergence? [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.
An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. Find the position and nature of the ¡mage.
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]
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 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]
Explain with the help of a diagram, why a pencil partly immersed in water appears to be bent at the water surface. [Delhi]
For which position of the object does a convex lens form a virtual and erect image? Explain with the help of a ray diagram. [All India]
Explain why a ray of light passing through the centre of curvature of a concave mirror, gets reflected along the same path. [Delhi]
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]
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]
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]
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]
A girl was playing with a thin beam of light from her laser torch by directing it from different directions on a convex lens held vertically. She was surprised to see that in a particular direction the beam of light continues to move along the same direction after passing through the lens. State the reason for this observation. [Foreign]
If a light ray IM is incident on the surface AB as shown, identify the correct emergent ray. [Delhi (C)]
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)]