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## Electricity ### Chapter 9 Electrical energy is fundamental to our modern lives. Electricity can travel along wires to light up our homes or school. It can make the sky light up during a flash of lightning. Your music system, television, mobile phones and laptops rely on different electrical sys...

## Electricity ### Chapter 9 Electrical energy is fundamental to our modern lives. Electricity can travel along wires to light up our homes or school. It can make the sky light up during a flash of lightning. Your music system, television, mobile phones and laptops rely on different electrical systems to work. Without it, we would find life to be very difficult, and certainly less entertaining. Have you ever tried to recharge your mobile phone without an energy source? ### What is electricity Electricity is a phenomena based on the presence and flow of electric charges. The movement of electrons produces electricity. Electrons have a negative charge and if two electrons come close, they repel each other. They move from one atom to another of a conducting material. Generating electricity means generating this movement of electrons. There are two types of electrical energy: ### Static electricity Static electricity is a type of electricity that does not move. When you rub certain materials together they become electrically charged. The friction between the two materials causes electrons to be removed from one of them and added to the other. The material that gains electrons becomes negatively charged. The opposite charges attract each other. If you run a plastic comb through your hair and bring it near small pieces of paper, the papers are attracted to the comb because the comb induces an opposite charge in the paper. Electricity can make your hair stand up when rubbed by a balloon. This kind of electricity is called static electricity. ### Dynamic electricity Dynamic electricity is a flow of electricity through a conductive material such as a copper wire. Lightning releases a large amount of electrical energy. However, the electric charge from lightning doesn't last long enough to power your radio or your TV. These devices require electric charges that flow continuously. They require electric current. The static electric charges do not flow continuously. Electricity can travel along wires to light or heat your home or school. ### Circuit diagrams Circuits are represented using symbols. Connecting wires are represented using a symbol [diagram shows a simple circuit diagram with components, wires and symbols] They are often (but not always) drawn with a battery, the positive terminal of the battery is connected to the positive (+) terminal. The electrons pass through the circuit and when they arrive at the bulb they make it heat up as shown in the figure.