Suppose that a light intensity of 20W/m² causes a current of 5×10^-6A to flow in a photocell. How much current will flow if the intensity is increased to 60W/m²?

The intensity is increased by a factor of 3, so there are 3 times as many photons hitting the photocell. That makes 3 times the current: 15×10^-6A

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