Step 1: List the known quantities
- Resistance, R = 10 Ω
- Current, I = 0.3 A
Step 2: Write the equation relating resistance, potential difference and current
V = IR
Step 3: Substitute in the values
V = 0.3 × 10 = 3 V
Author
AshikaExpertise
Physics Project Lead
High resistance means there is lower current and vice versa
In my experience, resistance can be tricky to grasp conceptually, because the definition 'opposition to current' is a bit difficult to pin down. This is how I explain resistance to my students:
Imagine you're playing a video game in which you are a tiny electron flowing through a wire. The wire from your point of view is this huge structure of metal ions arranged in a lattice. There are millions of other electrons flowing through the wire too. Every time an electron hits the lattice, the electron transfers some of its energy to the lattice and the lattice vibrates more and more. The more it shakes, the more you collide with it.
This is exactly what resistance is, the wire heats up due to the collisions of electrons with the lattice of the metal ions in the wire. The hotter it gets, the more collisions there are. The more collisions there are, the hotter it gets... and on and on and on.
Voltage, current, resistance formula triangle
Calculate the potential difference through a resistor of resistance 10 Ω if there is a current of 0.3 A through it.
Step 1: List the known quantities
Step 2: Write the equation relating resistance, potential difference and current
V = IR
Step 3: Substitute in the values
V = 0.3 × 10 = 3 V
Remember that 'voltage' and 'potential difference' are the same, either wording will be accepted in your exam answers
to absolutely everything:
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Ashika graduated with a first-class Physics degree from Manchester University and, having worked as a software engineer, focused on Physics education, creating engaging content to help students across all levels. Now an experienced GCSE and A Level Physics and Maths tutor, Ashika helps to grow and improve our Physics resources.