Hots physics question of board class

       1. Name the part of the human eye that helps in changing the focal length of the eye lens.

       2. Name the component of white light which deviates

      (i) The least and    (ii) The most while passing through a glass prism.

      3. Why does the clear sky appear blue? How would the sky appear in the absence of earth’s atmosphere?

    4. Why does the sun seem to rise two minutes before the actual sunrise and set two minutes after the actual       sunset? Explain with the help of labeled diagram.

5.With the help of ray diagrams, show the formation of image by                                                                      (i)    a hypermetropic eye and (ii) correction of hypermetropic eye  by using an appropriate lens

     6. Draw the pattern of magnetic field lines around a current carrying straight conductor. How the strength of the   magnetic field does produced change:

    (i) With the distance from the conductor?

    (ii) With an increase in current in a conductor?

    7. Draw the following diagram, in which a ray of light is incident on a concave/convex mirror, on your answer sheet. Show the path of this ray, after reflection, in each case.

.8. For the series combination of three resistors establishes the relation: R = R1+ R2 + R3 where the symbols have their usual meanings.

09. What is meant by electric circuit? Why does electric current start flowing in a circuit the moment circuit is complete? When do we say that the potential difference across a conductor in a circuit is 1 volt?

Calculate the potential difference between the two terminals of a battery if 12 joules of work is done in transferring 2 coulombs of charge.

10. What is meant by “sustainable management”? Why is reuse considered better than recycling?

11. Amit lives in Delhi and is much concerned about the increasing electricity bill of his house. He took some steps to save electricity and succeeded in doing so.
(i) Mention any two steps that Amit might have taken to save electricity.
(ii) Amit fulfilled his duty towards the environment by saving electricity. How?
(iii) Which alternative source of energy would you suggest Amit to use?

12. What is meant by resistance of a conductor? Name and define its SI unit. List the factors on which the resistance of a conductor depends. How is the resistance of a wire affected if —
(I) its length is doubled,
(ii) its radius is doubled

13. The absolute refractive indices of glass and water are 3/2 and 4/3 respectively. If the speed of light is 3 x 108 m/s, calculate the speed of light in

(i) vacuum,
(ii) water.

14. Write any five characteristics of a good fuel.

15. If the image formed by a mirror for all positions of the object placed in front of it is always erect and diminished, what type of mirror is it? Draw a ray diagram to justify your answer. Where and why do we generally use this type of mirror?

16. What is meant by scattering of light? Use this phenomenon to explain why the clear sky appears blue.

17. Two electric circuits I and II are shown below
(i) which of the two circuits has more resistance?
(ii) Through which circuit more current passes?
(iii) In which circuit, the potential difference across each resistor is equal?

            

18. Write a short note on

1. Solar energy

2. Wind energy

3. Tidal energy

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