Yahoo 知識+ 將於 2021 年 5 月 4 日 (美國東岸時間) 停止服務。從 2021 年 4 月 20 日 (美國東岸時間) 起,Yahoo 知識+ 網站將轉為僅限瀏覽模式。其他 Yahoo 資產或服務,或你的 Yahoo 帳戶將不會有任何變更。你可以在此服務中心網頁進一步了解 Yahoo 知識+ 停止服務的事宜,以及了解如何下載你的資料。

Ls 發問於 科學及數學物理學 · 5 年前

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?

1 個解答

評分
  • 天同
    Lv 7
    5 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.

還有問題嗎?立即提問即可得到解答。