Potential Energy of an electron in a parallel plate capacitor

In summary, the potential energy of an electron in a parallel plate capacitor can be calculated using the equation 1/2mv^2 = qV = PE, where q is the charge, V is the voltage, and PE is the potential energy. However, there is also another equation, 1/2QV, which represents the energy stored in the capacitor. In the case of the electron problem, the equation 1/2mv^2 = qV = PE should be used to calculate the potential energy.
  • #1
Seydlitz
263
4

Homework Statement



What is the potential energy of an electron in a parallel plate capacitor if kept on the negative plate before being released?

Homework Equations



1/2mv^2 = qV = PE
Capacitor Energy = 1/2QV

The Attempt at a Solution


1/2mv^2 = qV = PE

However if I'm not mistaken there's also 1/2QV equation that states the energy stored in a capacitor? Which one then should I choose for this electron problem? The normal qV or the 1/2qV?
 
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  • #2
The force on the electron due to the E field of the capacitor is F = qE = eV/d.
As it falls the distance between plates, the work done by this force is W = F*d = eV.
So your have it right. The 1/2QV must for something else, perhaps the electrical energy stored in the capacitor.
 

Related to Potential Energy of an electron in a parallel plate capacitor

1. What is the formula for calculating the potential energy of an electron in a parallel plate capacitor?

The formula for calculating the potential energy of an electron in a parallel plate capacitor is U = (1/2)QV, where U is the potential energy, Q is the charge on the capacitor, and V is the voltage across the capacitor.

2. How is the potential energy of an electron related to the distance between the plates of a parallel plate capacitor?

The potential energy of an electron is directly proportional to the distance between the plates of a parallel plate capacitor. This means that as the distance between the plates increases, the potential energy of the electron also increases.

3. What is the role of charge and voltage in determining the potential energy of an electron in a parallel plate capacitor?

The potential energy of an electron in a parallel plate capacitor is directly proportional to both the charge on the capacitor and the voltage across the capacitor. This means that as the charge or voltage increases, the potential energy of the electron also increases.

4. How does the potential energy of an electron change when the capacitance of a parallel plate capacitor changes?

The potential energy of an electron is not affected by changes in capacitance of a parallel plate capacitor. It is solely determined by the charge on the capacitor and the voltage across it.

5. Can the potential energy of an electron in a parallel plate capacitor be negative?

Yes, the potential energy of an electron in a parallel plate capacitor can be negative. This occurs when the electron's charge is of opposite sign to that of the capacitor's charge, causing the potential energy to be negative in value.

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