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A photocell is illuminated by a small bright source placed 1 ~m away. When the same source of light is placed 1 2 ~m away, the number of electrons emitted by photo cathode would

Options

  1. Adecrease by a factor of 4
  2. Bincrease by a factor of 4
  3. Cdecrease by a factor of 2
  4. Dincrease by a factor of 2

Correct answer

B. increase by a factor of 4

Step-by-step solution

I 1 r^2

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