Energy In Capacitors
Energy Storage In Capacitors?
How Much Energy Can Be Stored In A Capacitor?
Notes On Energy In Capacitors
Problems

Why Would You Want To Store Energy in Capacitors?

        Storing energy is very important.  You count on the energy stored in your gas tank if you drove a car to school or work today.  That's an obvious case of energy storage.  There are lots of other places where energy is stored.  Many of them are not as obvious as the gas tank in a car.  Here are a few.

        Capacitors can't really be used to store a lot of energy, but there are many situations in which a capacitor's ability to store energy becomes important.  In this lesson we will discuss how much energy a capacitor can store.  Your goal for this lesson is this.         Capacitors are often used to store energy.
How Much Energy Can Be Stored In A Capacitor?

        To calculate how much energy is stored in a capacitor, we start by looking at the basic relationship between voltage and current in a capacitor.  First, here is the circuit symbol for a capacitor with the current into the capacitor and the voltage across it defined.

Then, the relationship between the current and the voltage in the capacitor is given by:

 i(t) = C dv(t)/dt

        Once we have this relationship, we can calculate the power - the rate of flow of energy into the capacitor - by multiplying the current flowing through the capacitor by the voltage across the capacitor.  And, once we have the power - the rate of flow of energy into the capacitor - we can eventually calculate the energy stored in the capacitor.  We know:

P(t) = i(t)v(t)


Some Things To Note About The Energy Storage Formula

        Note the following about the energy stored in the capacitor.

Note also the following observations. And some final points to note.

Problems

Links to Other Lessons on Capacitors Send your comments on these lessons.