## Electric Circuits

WHAT IS AN ELECTRIC CIRCUIT?

An electric current is the path in which electrons from a voltage or current source flow to form an electric charge. Some insulating materials become electrically charged when they are rubbed together.

A circuit always needs a power source, such as a battery, with wires connected to both the positive (+) and negative (-) ends. A battery is also known as a cell. A circuit can also contain other electrical components, such as switches, bulbs, buzzers or motors, which allow electricity to pass through. Electricity will only travel around a circuit that is complete, that means it has no gaps.

There are two types of electric charges: positive and negative. Charges that are the same (e.g. positive and positive) repel, while unlike charges (e.g. positive and negative) attract. An object is negatively charged if it has an excess of electrons, and is otherwise positively charged or uncharged.

Definitions:

• Electron – is a very small piece of matter and energy.
• Voltage – is a force that makes electricity move through a wire.
• Resistor – is a restriction of current. It limits the electrical current that flows through a circuit (resistors can be linked in various combinations to help make a circuit – series or parallel).
• Electronic component – is a device used to affect electrons.
• Electric charge – is the physical property of matter that causes it to experience a force when placed in an electromagnetic field.

WHAT ARE SERIES AND PARALLEL CONNECTIONS?

When making an electrical circuit the components can be connected in series or in parallel. The characteristics of the current and potential difference (voltage) are different in series and parallel circuits.

Series connections are components that are connected one after another on the same loop of the circuit. The current that flows across each component connected in series is the same.

The circuit diagram shows a circuit with two lamps connected in series. If one lamp breaks, the other lamp will not light.

Parallel connections are components that are connected on separate loops. The current is shared between each component connected in parallel. The total amount of current flowing into the junction, or split, is equal to the total current flowing out.

The circuit diagram shows a circuit with two lamps connected in parallel. If one lamp breaks, the other lamp will still light.

JUMP STARTING A CAR?

When you jump start a car you are basically putting a working battery in parallel with the drained one, giving the circuit some energy by circumventing the dead battery.

You don’t connect the two negative terminals as this would mean the circuit would have virtually no load and be somewhat dangerous. You actually do connect the negative terminals, but you do it through the body of the car to give the circuit some resistance, stopping everything from burning out from the high current.

Park your car (that is dead) facing or next to the car giving you the jump and open both the bonnets. Both cars should be off.

1. Clamp one end of the red cable (+) to the positive (+) terminal on the battery of the dead car.
2. Clamp the other end of the red cable (+) to the positive (+) terminal but this time on the battery of the car you are trying to jump start from.
3. Clamp one end of the black cable (-) to the negative (-) terminal on the battery of the car you are trying to jump start from.
4. Clamp the other end of the black cable (-) to the some unpainted metal screw or knob near the battery of the dead car. This is to ground the connection. Do not connect it to the negative (-) of the car’s battery or have it touch the engine from the car you are trying to jump start from.

Now you can start the engine of the car you are trying to jump start from. Let it run for a few minutes so the power starts flowing. Next, start the dead car and let that run for a few minutes as well.

https://simple.wikipedia.org/wiki/Electrical_circuit

http://www.rkm.com.au/ANIMATIONS/animation-electrical-circuit.html

https://simple.wikipedia.org/wiki/Electron

https://simple.wikipedia.org/wiki/Voltage

https://simple.wikipedia.org/wiki/Resistor

https://en.wikipedia.org/wiki/Electronic_component

https://en.wikipedia.org/wiki/Electric_charge

http://electricalengineeringforbeginners.blogspot.co.uk/2009/08/what-is-electric-circuit.html