Dioptre is the unit of power of

A. convex mirrors

B. concave mirrors

C. concave lenses

D. lenses irrespective of types

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  1. When ice melts, Its volume
  2. Which of the following apparatus is used in the electrolysis of water?
  3. Who first established the fact that the earth revolves round the sun?
  4. A car parked in the sun with its windows closed gets terribly hot inside. This is due to
  5. Skating on ice is possible because
  6. The period of oscillation of a simple pendulum depends upon
  7. A proton is
  8. The inside of both the walls of a thermos flask is silvered i.e., on the vacuum side in order to reduce…
  9. The image formed by a plane mirror is
  10. Every action has an equal and opposite reaction is Newton's law of Motion
  11. Pieces of camphor placed on water move about rapidly. This is because of
  12. A hydraulic brake in an automobile uses
  13. The radius of curvature of a spherical mirror is
  14. Out of the following, name the fluorescent substance.
  15. X-rays are
  16. Why is it cool near an open pond on a hot summer day?
  17. The sun continuously produces an enormous amount of energy. This la due to
  18. The heat produced in a conductor due to the passage of a current through it is proportional to
  19. The temperature of a large bucket-full of hot water (a few degrees below boiling point) is lower than…
  20. When ice just melts
  21. Cyclotron is an apparatus used
  22. A pair of stars that revolve round each other is
  23. What la the minimum velocity required for a rocket to overcome earth's gravity and travel into space?
  24. The radiator in a car serves to
  25. The radius of an atom is approximately
  26. The filament lamp is an example for
  27. The heating element often used in an electric iron is
  28. The Indian Satellite System used for domestic communications, television and meteorology is known as
  29. Heat is transmitted from one end of a metal rod to its other end by the method of
  30. If a band is played on the moon the sound will