Question about gold leaf electroscope.?

2016-12-01 3:21 am

The metal cap of the gold leaf electroscope is connected to the positive terminal of an EHT which is powered on.

My book said the size of the metal cap will not change the charge distribution. Therefore the divergence of the gold leaf will not charge.

But I think that when the size of the metal cap increase, the average positive charge per surface area decrease, so the magnitude of charge in the gold leaf decrease, the repulsive force is less then it is less diverge.

Why am I wrong? Thanks

回答 (1)

天同

2016-12-01 8:03 am

✔ 最佳答案

The EHT will maintain a constant potential at the metal cap of the electroscope. If the size of the cap increases, its capacitance (i.e. its ability to hold charges) will increase accordingly. As such, charges will flow from the EHT towards the cap so as to maintain its original potential. (Remember that: charge = capacitance x voltage, when voltage is kept constant by the EHT, an increase of capacitance resulted in an increase of charge).

Therefore, the charges per unit area remains unchanged. The charges on the gold leaf is the same as before. There is no change in its divergence.

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