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Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R Assertion A : Photodiodes are used in forward bias usually for measuring the light intensity. Reason R: For a p - n junction diode, at applied voltage V the current in the forward bias is more than the current in the reverse bias for V z > ± V ≥ V 0 where V 0 is the threshold voltage and V z is the breakdown voltage.

Options

  1. ABoth A and R are true and R is correct explanation A
  2. BBoth A and R are true but R is NOT the correct explanation A
  3. CA is false but R is true
  4. DA is true but R is false

Correct answer

C. A is false but R is true

Step-by-step solution

Photodiodes are operated in reverse bias condition. The change in saturation reverse current in a photodiode with reverse bias is directly proportional to the change in light intensity, thus can be precisely measured. Current in forward bias (for applied voltage V ≥ V 0 ) is always greater than current in reverse bias (for V ≤ V z ) in a p - n junction diode. Hence, Assertion if false but Reason is true.

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