Chapter 6 Lesson 2

How can electricity flow? When an object gains of loses electrons, it has an electric charge. Similar to magnetic force, unlike charges attract each other, an like charges repel each other. This attraction or repulsion is called electric force.

Electric Current Electrons flow from negatively charged objects to positively charged objects. The flow of electrons is called electric current.

Electric Current Matter that conducts, or carries electrons more easily than others is called a conductor. An electric circuit is any path along which electrons can flow. (Copper and aluminum are often used as conductors.)

Electric Current Conductors are wrapped with a material called an insulator. An insulator is a material that does not carry electrons. (Rubber, plastic, glass, and air are good insulators.) Insulators resist the flow of electrons through them.

Electric Current Some materials are neither conductors nor insulators. Inside many electronic devices are materials that do not completely stop the flow of electrons. However, they resist, or reduce the electric current in the device, and allow electric energy to be changed into other forms. (A light bulb, resists the flow of electrons. This resistance produces heat, and the filament gets hot enough to glow, giving off light!)

Electric Current The amount of electric charge is measured in amperes, or amps. Resistance is measured in ohms. (How much electricity can move through a circuit. Or how many items can be run off of a given circuit.)

Electric Current Voltage (Volts) is the measure of electric potential. (Max power, of what can be given from an electric source.)

Electric Safety Plugging too many appliances into a power outlet dangerously heats wires and can start a fire.

Electric Safety A fuse helps protect against large electrical currents, by breaking the current when it detects too much energy moving through a circuit. (short circuit, or a rush of energy flowing from an outlet or switch.)

Electric Safety Bathrooms and kitchen outlets have small buttons saying “test” and “reset.” These are ground fault interrupter (GFI) switches. GFI switches will turn an outlet off if a short circuit forms.

Electric Safety A surge protector prevent sudden spikes in current from entering electronics and damaging them.