Introduction
If you've ever sat watching a thunderstorm, with mighty lightning bolts darting down from the sky, you'll have some idea of the power of electricity. A bolt of lightning is a sudden, massive surge of electricity between the sky and the ground beneath. The energy in a single lightning bolt is enough to light 100 powerful lamps for a whole day or to make a couple of hundred thousand slices of toast!
Electricity is a type of energy that can build up in one place or flow from one place to another. When electricity gathers in one place it is known as static electricity (the word static means something that does not move); electricity that moves from one place to another is called current electricity.
For an electric current to happen, there must be a circuit. A circuit is a closed path or loop around which an electric current flows. A circuit is usually made by linking electrical components together with pieces of wire cable. In a flashlight, there is a simple circuit with a switch, a lamp, and a battery linked together by a few short pieces of copper wire. When you turn the switch on, electricity flows around the circuit. If there is a break anywhere in the circuit, electricity cannot flow. If one of the wires is broken, for example, the lamp will not light. Similarly, if the switch is turned off, no electricity can flow. This is why a switch is sometimes called a circuit breaker.
In this WebQuest you will explore how electricity flows in a current from a battery to a light globe, giving it power. You will learn about how an electric current flows through a circuit to light the globe and use scientific language to describe this process.
SUCCESS CRITERIA
To be successful you will be able to:
- Understand that electrons (the electric current) can only flow 1 way around a circuit from a battery
- Identify the role that wire plays in an electric circuit
- Explain what will stop an electric current from flowing in a circuit
- Learn about the following scientific words:
Electrons
Current
Resistance
Load
Voltage
Task
In this WebQuest you will work in pairs or groups of 3 to:
- Read the information
- Watch the video clips
- Answer the questions
You will be taking part in an experiment to test your knowledge in the next lesson!
Process
Imagine riding a bicycle on a path around a lake. If there are no obstacles on the path, you can
easily complete the circuit and end up back where you started. In the same way, if there are no
breaks in an electrical circuit, a current will start at a battery and flow around the circuit until it is
back at the battery. If when cycling an obstacle falls on the cycle path behind you, it won't stop
you completing the circuit because you have already passed that point. However, if a break
occurs anywhere in an electric circuit at any time, the electricity stops flowing.
On the bicycle path, there may be a tunnel to ride through or a bridge crossing over a stream,
but these won't stop your progress. In an electric circuit, there may be a light globe or a door bell
that uses the electricity but, like the tunnel or the bridge, they do not stop the flow of electricity.
Perhaps a train line crosses the cycle path. When a train is due, warning lights flash and a gate
comes down across the path, blocking the way. Until the train has passed and the gate is lifted,
you will not be able to continue. A switch in an electric circuit is like that gate. It stops and starts
the flow of electricity.
Electric current
Everything is made up of atoms, each of which has a positively charged core (called a nucleus) and number of concentric shells surrounding it. These shells contain tiny negatively charged particles called electrons. In metals, electricity is the flow of electrons from the outer shell of one atom to the outer shell of another. This flow of electrons is called a current. The path of the current is called a circuit.
Electric circuit
A simple circuit consists of a battery to provide power, wires to carry the current and a load that uses the electricity; for example, light globe. The wires are connected from the positive end to the negative end of the battery. In between, a light globe is attached. A switch can be added to create or break the circuit so the globe can be switched on and off.
Voltage
To make the electricity flow, a force is needed to push the electrons around the circuit. This force, which is called the voltage, is provided by the battery. The electrons flow from the negative terminal of the battery, along a wire to the load, then along another wire to the positive end of the battery.
Resistance
As a current flows through a circuit, the wire exerts a force against the flow of electrons. This force is called resistance. It causes friction by slowing down the movement of electrons. A thin wire slows the electrons more than a thick wire and creates more resistance. This is the same for the longer wire. It takes energy for electrons to move against the resistance along a wire.