Electrical energy is part of our everyday lives at home, at work and at school. We use it for refrigeration, machines and lighting. Portable devices such as mobile phones, watches and many toys rely on batteries for electrical energy. Electric circuits are needed to allow energy to be transferred from a battery to light bulbs, motors and buzzers, where it is changed into light, movement or sound.
Big ideas addressed in this unit
Batteries, Circuits, Circuit Diagrams, Voltage, Electrons,
Light Bulbs and Switches.
What do we already know about electricity?
Construct and test electrical circuits and complete circuit diagrams.
A circuit diagram is a pictorial representation of an electric circuit. It includes standard symbols for different components and connections between these components.
This is what our circuit diagrams looked like before....
This is what our circuit diagrams look like now!
How does a light bulb work?
Inside a light bulb, there is a wire filament, which is often made of the metal tungsten. The filament looks like a spring, and it is connected to two metal rods. One of these rods is connected to the threaded outer metal case. The other rod is connected to the shiny metal part on the base of the light bulb. A non-metal spacer, which does not conduct electricity, separates the two connection points.
When electrical energy flows through it, the filament heats up to more than 2000 degrees Celsius. The flow of electrical energy through the filament heats the wire and causes it to glow white hot and give out a bright light. The heat from the filament in turn warms the light bulbs glass.
You’d think that being so hot the metal would burn up, however, fire needs oxygen- that’s why you can smother some fires and they go out. The bulbs are filled with nitrogen or neon gas, which means there is no oxygen in the bulb. This allows the filament to glow, without burning, for hundreds of hours.
How have scientific developments in the past led to the batteries
that we know today?
A battery is a device that stores chemical energy and makes it available in electrical form. Alessandro Volta’s original cell batter, the voltaic pile, was developed in 1799. A voltaic pile is made of discs of two different metals, for example, copper and zinc, separated with cloth soaked in a chemical solution. Volta’s battery was the first continuous and reproducible source of an electrical current.
The voltage of the battery is the amount of energy (or push) that the battery can generate and give to the electrons. The larger the voltage or the number of volts, the larger the capacity to energise electrons in a circuit.
Electron Role Play
We created a role play of the journey an electron takes through an electrical circuit.
There are three different components to this role play: Battery, Bulb and Electrons.
Battery- contains chemicals that possess chemical energy. When the chemicals react with eachother, they generate electrical energy. The battery is the source of electrical energy and provides the push for the electrons to move around the wire.
The battery provides a 'push' for the electrons to move as it supplies them with electrical energy.
Electrons- carry the electrical energy from the battery to the bulb- energy transfer
The electrons are located within the wires of a circuit, they collect energy from the battery and take it to the light bulb.
Bulb- changes the electrical energy into light and heat energy- energy transformation
The light bulb uses the electrical energy carried by the electrons and transforms it into heat and light energy.
Here are some pictures of our role play.
The electrons are collecting energy from the battery and delivering it to the light bulb.
The light bulb transforms the electrical energy to heat and light energy. Once the electrons stop moving and delivering the energy, the light bulb can no longer light up.