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Consider a set up with a power supply(dc voltage) and a photocell (metal plate + collector) and an ammeter. Frequency of light is constant.?
When V gradually increases from 0 (cathode linked to the collector), the photoelectric current is said to be increased until it reaches the saturated current. (from my book)
But from my exercise, it says it wont increase because the current is not contributed by the dry cell, but by radiation. Once the photoelectrons are emitted, they tend to go round the circuit and return to the illuminated metal. The dry cell cannot increase the number of photoelectrons.
Which one is correct?
- 天同Lv 75 年前最愛解答
You need to check if the circuit in your book and that in the exercise are identical.
From your description, if the dc power-supply cathode is linked to the photocell collector, the collector will be negatively charged. As a result, any increase of supply voltage will make the collector more negatively charged, and hence repel more electrons from reaching the collector. The photo current will decrease instead of increase.