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NEET2009PhysicsSemiconductorsActual

Assertion : A photocell is called an electric eye. Reason : When light is incident on some semiconductor its electrical resistance is reduced.

Options

  1. AIf both assertion and reason are true and reason is the correct explanation of assertion
  2. BIf both assertion and reason are true but reason is not the correct explanation of assertion
  3. CIf assertion is true but reason is false
  4. DIf both assertion and reason are false.

Correct answer

B. If both assertion and reason are true but reason is not the correct explanation of assertion

Step-by-step solution

Photo-conductive cell is based on the principle that when light is incident on some semiconductor, its electrical resistance is reduced. Such cells are used in solar batteries. Whereas photocell is used in electrolyte for giving theft warning in banks treasuries, etc., when the thief throws torch light on the cash box, the light is incident on a photocell placed there and a bell at some particular place rings.

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