CBSE Important Questions

Physics (Light)

1. Reflection/Refraction:

1. Where will the image be formed when the object is placed between the focus and the pole (infinity, pole) of the convex mirror?
2. With respect to air the refractive index of ice and that of rock salts are 1.31 and 1.54 respectively. Calculate the refractive index of rock salt with respect to ice.
3. With respect to air the refractive index of water and that of benzene are 1.33 and 1.50 respectively. Calculate the refractive index of benzene with respect to water.
4. Wavelength of radiation 850nm falls on a surface. Will this surface be visible or not? Explain.
5. A convex mirror used on a truck has 3m radius of curvature. If a bus is located at 5m from this mirror. Find the position, nature and size of the image.
6. What is the condition under which motion pictures can be clearly seen?
7. What is accommodation? What is the maximum variation in power of accommodation in human eye?
8. An object of size 5cm is placed at a distance of 25cm from the pole of a concave mirror of radius of curvature 30cm. Calculate the distance and size of the image formed. What will be the nature of the image?
9. An object of size 3cm is placed at a distance of 15cm from a convex lens of focal length 10cm. Calculate the distance and size of the image so formed. What will be the nature of image?
10. Light enters from air to glass plate having refractive index 1.50. What is the speed of light if the speed of light in air is m/s?
11. What is dispersion? Which color of light deviates more on passing through a prism? When two prisms are placed together with one inverted and white light is passed, what will be the result?
12. What are the conditions for the formation of rainbow?
13. Why do blue and yellow pigments give green colour on mixing? Explain as clearly as possible and support your answer with a diagram.
14. What are the values for the angle of incidence and angle of reflection for normal incidence?
15. What is the relation between the critical angle and the refractive index for a medium?
16. Explain the phenomenon of mirage in deserts and looming in the seas? Support your answer with diagrams. Why does a diamond glitter more? Which phenomenon does optic fiber work upon?
17. An object is placed 20cm in front of mirrors M₁ and M₂ separately and image is found to be formed at a distance of 15cm in front of it in case of M₁ and behind it in case of M₂. Find the focal length and kind of mirror in each case.
18. Give two differences between real and virtual images.
19. Derive mirror formula for a concave mirror.
20. Derive lens formula for a convex lens.
21. What is the critical angle of incidence? Prove .
22. What will be the colour of the red rose when placed separately in white light and blue light? Give reasons for your answer.

Physics Links
1.	Light
2.	Optical Instruments
3.	Nuclear Fission and Fusion
4.	Universe
5.	Electricity
6.	Sources of energy
7.	Rate of Chemical reactions