Naked Science Forum

On the Lighter Side => Science Experiments => Topic started by: Hayseed on 24/01/2020 00:05:52

Title: Electric Field Density
Post by: Hayseed on 24/01/2020 00:05:52

What would happen if........

We take an inflated balloon, and induced a strong uniform charge on the surface, hang it from the ceiling.....the balloon has a remotely controlled valve.  (long insulated rod)

Place an electroscope to indicate a half scale reading(45degrees).

Slowly release the air.

Does the electroscope, indicate a stronger, weaker or steady field?

Title: -
Post by: WefLiZ on 22/03/2021 10:40:24

I do not understand why the charge would not follow the direction of the field. It is the only one, it can not have an influence on electric field he fiels. Plus the initial velocity is zero. Or is it something else ....

Dejan

:shock:

Title: Re: Electric Field Density
Post by: Bored chemist on 22/03/2021 14:08:07

Interesting question.
I think the voltage would rise, in much the same way it does with an electrophorus.

As the balloon shrank (and assuming the skin to be alt least slightly conductive) the capacitance would fall but the charge has nowhere to go.
With a smaller capacitance, and the same charge, you have a higher voltage.

Title: Re: Electric Field Density
Post by: alancalverd on 25/03/2021 20:41:51

It's the principle of the Wimshurst generator: induce a charge on a capacitor then reduce the capacitance: the voltage increases.

Title: Re: Electric Field Density
Post by: Bored chemist on 25/03/2021 20:56:25

See also
https://en.wikipedia.org/wiki/Van_de_Graaff_generator
https://en.wikipedia.org/wiki/Kelvin_water_dropper