Topic 5c
Engineering a solution
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Learning aims
Learning aims
To recognise and recall the four main properties of electricity and how they are inter-dependent.
To be able to calculate values of current, voltage, resistance and power.
(Why am I doing this?)
(Why am I doing this?)
So that I can understand how ohm's law affects battery performance.
So that can design my own simple electronic circuits.
Activities
Activities
What's the difference between voltage, current and resistance?
What's the difference between voltage, current and resistance?
You will have heard of these terms before, but what do they actually mean?
Voltage, current and resistance are properties of electricity. They describe how electricity behaves. As we can't physically see electricity, it is useful to describe them in these terms instead.
Current
Current
Power
Power
Power can be thought of as the rate of energy transfer. In the case of electrical power, it is the rate at which current is 'pushed' through a component or circuit.
Why do you think the bulb below explodes?
Voltage
Voltage
Voltage describes the difference in electrical potential between one side of a component or circuit and the other. A useful analogy is to think of it a bit like electrical 'pressure'.
Resistance
Resistance
Resistance is a force which is trying to slow down the current, the flow of electrons. Resistance is inversely proportional to current. That means when resistance goes up, current goes down and vice versa.
Voltage and current explained
Voltage and current explained
The two excellent videos from the engineering mindset explain how voltage and current function.
Current explained.mp4Voltage Explained.mp4Visualising using the 'water analogy'
Visualising using the 'water analogy'
Because we can't 'see' electricity with our eyes alone, the water analogy is a useful way of visualising electron flow in a circuit.
Activity 1 - Ohm's Law
Activity 1 - Ohm's Law
Watch how the properties interact with each other by clicking the sliders in the simulator .
If you know two properties of electricity within a circuit or component, then you can calculate a third property. The relationship that describes this is called Ohm's Law.
Why we join batteries together
Why we join batteries together
Why do we connect batteries.mp4Safety - Do's and don'ts of joining batteries
Safety - Do's and don'ts of joining batteries
Activity 2 - Ohm's Law and batteries
Activity 2 - Ohm's Law and batteries
Have a go at adjusting the properties of resistance and voltage within the battery simulator below, noting:
How the battery polarity (direction) switches when a negative voltage is selected.
How the current increases when resistance decreases.
How current decreases when resistance increases.
How the filament (wire) temperature increases when voltage increases.
How the filament (wire) temperature increases when resistance decreases.
Activity 3 - Task list
Activity 3 - Task list
If you're feeling confident, have a go at calculating voltage, current and resistance by answering the questions on the 'calculations sheet' below. Remember to make a copy (and edit that).
If you are less confident and would rather have some additional support, have a go at this calculation sheet instead. You can also use the Ohm's Law Calculator on the right to help.
I don't mind which version of the worksheet you attempt, as long as you attempt all four questions.
When finished, attach it to the Google Classroom in your term's assignment for feedback.
DC Circuit Simulator
DC Circuit Simulator
Click to view the page whole screen from the University of Colorado PhET simulator website. A fantastic learning resource!
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