That is why wires are made of metal. They allow current to flow from one point to another point without any resistance. Wires are usually covered with rubber or plastic. This keeps the wires from coming in contact with other wires and creating short circuits. High voltage power lines are covered with thick layers of plastic to make them safe, but they become very dangerous when the line breaks and the wire is exposed and is no longer separated from other things by insulation.
Resistance is given in units of ohms.
Common resistor values are from 100 ohms to 100,000 ohms. Each resistor is marked with colored stripes to indicate it s resistance. To learn how to calculate the value of a resistor by looking at the stripes on the resistor, go to Resistor Values which includes more information about resistors. Variable Resistors Variable resistors are also common components. They have a dial or a knob that allows you to change the resistance.