The power of a lens is

A. equal to its focal length

B. equal to its radius of curvature

C. equal to the reciprocal of its focal length (in metres)

D. equal to twice its focal length

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  1. In a microphone
  2. In a refrigerator, the refrigerant is
  3. When light passes from air to glass, its velocity in glass
  4. A star contains
  5. The image formed by a plane mirror is
  6. The source of electric energy in an artificial satellite is
  7. The property of a fluid by which it resists relative motion within itself is known as
  8. Of the following which has got the highest frequency?
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  18. Halley's comet appears in the heavens once in
  19. A timer in a race is at the finish line. He should start his stop watch
  20. The base of an electric iron is brightly polished mainly
  21. The neutron, one of the constituent particles of which the nuclei of atoms are composed was discovered…
  22. Which of the following wires of same dimensions offers least resistance to the ,flow of current?
  23. The radiator in a car serves to
  24. Nuclear fusion is a process in which
  25. The Indian Satellite System used for domestic communications, television and meteorology is known as
  26. The device used to record the sound is
  27. The image of an object formed in a plane mirror
  28. In a hydraulic pressure
  29. A nuclear reactor is said to have become 'critical' when
  30. The colour of the light which travels through glass with minimum speed is