Lesson · P.5.2

Voltage, current and resistance

Voltage, current and resistance defined together through Ohm's law, V = I × R, plus the rule that resistance simply adds when components sit in series, the calculation the HESI A2 physics subtest builds its circuit questions around.

ObjectiveP.5.2Read4 minExam weightElectricity and Magnetism ≈ 16% of Physics

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What you will be able to do

You can define voltage, current and resistance and name the unit each one is measured in.
You can rearrange Ohm's law to solve for voltage, current or resistance, whichever one a question leaves out.
You can find the total resistance of components wired in series and use it to work out the current in a simple circuit.

What the lesson concludes

Voltage is the potential difference that pushes charge through a circuit, measured in volts.
Current is the rate at which charge flows, measured in amperes.
Resistance is whatever opposes that flow, measured in ohms, and Ohm's law ties all three together as V = I × R.
When components sit in series, their resistances simply add to give the total resistance.
Given any two of voltage, current and resistance, Ohm's law solves for the third one: I = V / R or R = V / I.