Understanding Capacitor Energy Storage: Clarifying Charge and Energy Units

[leelsund]

I guess this is a simple question and I can't find clarification on it any where

If the total charge on each plate of a parallel plate capacitor is 1200 joules then is the total energy stored in that capacitor 2400 joules. Lol might seem dumb but I just want to make sure this was correct

Thanks

 

[Dale]

the total charge on each plate of a parallel plate capacitor is 1200 joules then

Charge is measured in units of coulombs, not joules.

 

[leelsund]

Charge is measured in units of coulombs, not joules.

k then does the charge on each plate = total charge

so 1200 on one plate 1200 on the other = 2400

 

[mikelepore]

Capacitor charge Q is defined so that there is charge separation with +Q on the positive plate and also -Q on the negative plate, when we say that the capacitor voltage is V=Q/C and the energy stored is (1/2)CV^2.

(Note that a total for +Q and -Q would always be zero.)

 

[leelsund]

Capacitor charge Q is defined so that there is charge separation with +Q on the positive plate and also -Q on the negative plate, when we say that the capactor voltage is V=Q/C and the energy stored is (1/2)CV^2.

(Note that a total for +Q and -Q would always be zero.)

total energy stored in a capacitor is split between the 2 plates. So say the capacitor stores 2 joules of energy does each plate hold 1 joule of charge.

 

[mikelepore]

Don't think of each plate holding half of the energy. Think of the energy being in the fact that +Q and -Q are attracted to each other but not allowed to move toward each other because of the insulation in the spacing.

 

[leelsund]

Don't think of each plate holding half of the energy. Think of the energy being in the fact that +Q and -Q are attracted to each other but not allowed to move toward each other because of the insulation in the spacing.

The question I have is a parallel plate capacitor holds a charge of 1200 joules on each plate. It has a potential difference of 110 volts applied to it what is the capacitance of the capacitor in farads

 

[mikelepore]

What DaleSpam said above. If the question says "a charge of 1200 joules" the question is incorrectly worded. I would ask the writer of the question if they mean "a charge of 1200 coulombs." If they say yes, then Q is 1200 coulombs.

I have never heard anyone refer to energy per plate.