Page No 168:
Question 2:
The radius of curvature of a spherical mirror is 20 cm. What is its focal length?
Page No 171:
Question 2:
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?
Page No 176:
Question 1:
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?
Page No 176:
Question 2:
Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass? The speed of light in vacuum is 3 × 108 m s−1.
Page No 176:
Question 4:
Material medium | Refractive index | Material medium | Refractive index |
Air | 1.0003 | Canada Balsam | 1.53 |
Ice | 1.31 | - | - |
Water | 1.33 | Rock salt | 1.54 |
Alcohol | 1.36 | - | - |
Kerosene | 1.44 | Carbon disulphide | 1.63 |
Fused quartz | 1.46 | Dense flint glass | 1.65 |
Turpentine oil | 1.47 | Ruby | 1.71 |
Benzene | 1.50 | Sapphire | 1.77 |
Crown glass | 1.52 | Diamond | 2.42 |
You are given kerosene, turpentine and water. In which of these does the light travel fastest? Use the information given in Table.
Page No 176:
Question 5:
The refractive index of diamond is 2.42. What is the meaning of this statement?
Page No 184:
Question 2:
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 convex lens if the image is equal to the size of the object? Also, find the power of the lens.
Page No 186:
Question 7:
We wish to obtain an erect image of an object, using a concave mirror of focal length 15 cm. What should be the range of distance of the object from the mirror? What is the nature of the image? Is the image larger or smaller than the object? Draw a ray diagram to show the image formation in this case.
Page No 186:
Question 9:
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.
Page No 186:
Question 11:
A concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object placed from the lens? Draw the ray diagram.
Page No 186:
Question 13:
The magnification produced by a plane mirror is +1. What does this mean?
Page No 186:
Question 15:
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.
Page No 186:
Question 16:
Find the focal length of a lens of power −2.0 D. What type of lens is this?
Page No 186:
Question 17:
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?
