Voltage, current and resistance explained simply, Ohm's law with a worked numerical, and series vs parallel in one glance.
The three quantities
- Current (I) — flow of charge, measured in amperes (A).
- Voltage (V) — the push that drives current, measured in volts (V).
- Resistance (R) — opposition to current, measured in ohms (Ω).
Ohm's Law
V = I × R. Rearranged: I = V/R and R = V/I.
Worked example: A 6 V battery drives current through a 3 Ω resistor. I = V/R = 6/3 = 2 A.
Series vs parallel
- Series: one path. Same current everywhere. Total R = R1 + R2 + ...
- Parallel: multiple paths. Same voltage across each. Total R is less than the smallest branch.
Exam tip: write the formula, substitute with units, then solve — markers give marks for the correct substitution step.