Electronics // Circuits
Ohm's law
For a resistor, voltage equals current times resistance (V = I × R). Rearranging it gives the current a circuit will draw or the resistor a part needs.
Quick check
A 9 V battery drives a 450 Ω resistor. The learner works out the current in milliamps and explains each step.
Ask this to see whether the topic is secure.
Topic // Mastery
What mastery looks like
What a learner can do once this topic is secure.
- Calculates any one of voltage, current or resistance from the other two, with units
- Rearranges V = I × R for the unknown before substituting numbers
- Checks an answer by estimating whether the current should be large or small
Topic // Map
Where this fits
What to learn first and what this topic opens up, with the reason for each link. Required links come first.
- RequiredMust come first
- HelpfulHelps, but not essential
Before this
2 topics- Current, voltage and resistanceRequired
Circuits // Ages 11 to 14
Ohm's law relates the three quantities
- Solving Linear EquationsHelpful
Mathematics // Algebra // Ages 11 to 14
Rearranging V = I × R is solving a one-step equation
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Ohm's law
Ages 12 to 15 // Method
Leads to
1 topic- Light-emitting diodesHelpful
Components // Ages 11 to 14
Ohm's law picks the series resistor
Electronics // Circuits