 In the previous video, we looked at the link between voltage and current and saw that voltage times current gives us power. However, there is another relationship between voltage and current, and it is called Ohm's Law. But before I can tell you about Ohm's Law, I need to tell you about a new quantity called resistance. Electronic components like resistors, light bulbs, even wires have a property which we call resistance. And resistance indicates how hard it is to move electrons through an object. So if an object is a really good conductor, like a metal, then it has a low resistance, and it's easy to get an electrical current to move through it. If an object is a poor conductor, like plastic or rubber, then it has a high resistance, and electricity will not flow through it easily. The symbol that we use to represent resistance is R. And the unit of resistance is Ohm's. So to give you an idea of how big an Ohm is, wires that connect components in circuits have resistance of about 0.01 Ohms. This is very low, indicating that the wires are good conductors of electricity. An incandescent light bulb will have a resistance of approximately 10 Ohms when it is cold and about 150 Ohms when it heats up and produces light, but it's still a reasonably good conductor. However, the insulation around a wire could easily have a resistance of a billion Ohms. And high resistance indicates that it is a good insulator, and electricity will not pass through it easily.