Solve Two Electric Field and Capacitor Problems with Homework Help!"

[gonzalo12345]

Homework Help! please

Homework Statement

Two problems:

1. A Van de Graff machine has an electric field of 2000 N/C at a distance of .3 meters. What electrostatic potential energy would a proton have there?
2. How long would a 3 Farad capacitor light a 60 Watt bulb?

Homework Equations

Capacitor = Q/V

The Attempt at a Solution

I don't know where to start and solve those problems, I need help

 

[Mike Cookson]

2.
It is easy if the question also has a voltage or you can assume it to be something like mains (240V UK).

C = Q/V(1), we also know that P = IV(2) and Q = IT(3)

Rearrange (2) to get it in the form I = P/V and then substitute into (3) Gives...
Q=(PT)/V. (4)

Now rearrange (1) to give Q=CV and substitute into (4) This Gives...
CV=(PT)/V or (CV^2)/P = T

1. - It's too late/early for me to start thinking about it.