 Now we can also look at the energy in a capacitor. So capacitors, well, it's a device that stores charge. And when it stores that charge, it's storing it with a voltage. Now, it takes some energy to put that charge and voltage on the capacitor. And I can release that energy if the capacitor discharges. So there's got to be some sort of measure of energy that's related to the charge and the voltage. So our equation for the energy in a capacitor ends up being this one, where u is the energy, q is the charge, and delta v is the voltage. The half comes in because I don't build up all the charge instantaneously. It kind of comes up over a small amount of time. Now, when I take a look at the units, charge is going to have units of coulomb. And voltage is going to have a unit of volt. But let's remember what that voltage was originally defined as. It was the electric potential energy per charge. So it was a joule per coulomb. So my two coulombs are going to be able to cancel out. And indeed, my energy is measured in joules. I also have a couple of alternate ways to write this equation. And these alternate equations come from my definition of the capacitance being related to the charge and the voltage. Well, if I use these sorts of equations, what I see is that I can also express my energy in terms of the capacitance and the voltage or in terms of the charge and the capacitance. So all three of these are ways I can represent the energy, depending on whether I've got the charge and voltage, the capacitance and voltage, or the charge and capacitance. So that's my energy on a capacitor. Just a quick view.