As said in the video, gravity and electricity are similar. When talking about gravity, we have the HEAVY BALL and the GROUND (earth). Gravitational force causes the BALL to want to be close to the GROUND. When talking about electricity, we have the PLUS CHARGE and the MINUS CHARGE. Electrical force causes the CHARGES to want to be close to each other.

When we lift the ball off the ground, we are giving it what we call GRAVITATIONAL POTENTIAL ENERGY. In much the same way, when we pull the plus charge away from the minus charge, we are giving it ELECTRICAL POTENTIAL ENERGY. The amount of energy increases the higher we lift the ball up or the farther away we pull the plus charge. When released, the ball will rush back to the ground and the plus charge will rush back to the minus charge.

Lifting the ball off the ground gives it some HEIGHT. Pulling the plus charge away from the minus charge gives it some DISTANCE. This distance measures VOLTAGE. The farther away we pull the plus charge from the minus charge, the greater the voltage is.

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1. Gravitational force and Electrical force are similar, even in the mathematical description. Gravitational force occurs between two objects with MASS, while electrical force occurs between two objects with CHARGE. The formula for gravitational force is given by:



while the formula for electrical force is given by:



Notice that these equations look similar; both forces are inversely proportional to the distance between the two objects squared, and both have a proportionality constant. As mentioned earlier, the only difference is that gravitational force occurs between two objects with MASS, while electrical force occurs between two objects with CHARGE.

2. Energy cannot be created nor destroyed; it can only be converted from one form to the other. This also applies here. The gravitational/electrical potential energy comes from the WORK DONE in lifting the ball off the ground or pulling the charges apart. Work is a form of energy, and in the case of the ball and the ground, it is converted into gravitational potential energy, while in the case of the charges, it is converted into electrical potential energy.

3. If the two charges are kept separate, the potential energy between the two remains the same. We say that energy is stored in the separation of charges. If we let go one of the charges, it will come rushing back towards the other one. In other words, the potential energy it initially has is now converted into kinetic energy and the object gains speed. Again, the potential energy did not come out of nowhere and just disappear into thin air; it is merely converted from one form of energy to the other.

4. Voltage is measured by the separation distance between the two charged objects. The farther apart the two charges are, the higher the voltage is, and more energy is stored in the separation. This is analogous to the ball and the ground: the higher we lift up the ball, more gravitational potential energy is store in the height. In the case of the lifted ball and the ground, we say that the ball is at a higher POSITION than the ground. In the case of the charges, we say that one of the charges is at a higher POTENTIAL (not to confuse with POTENTIAL ENERGY) than the other one. In fact, "voltage" is simply another way of saying "potential difference." The potential energy that is converted from the work done in separating the charges is STORED in the difference of potential between one charge and the other.