Glossary
voltage
Voltage is electrical pressure — the push that drives current around a circuit. It is measured in volts and is written as V in Ohm's law, V = I × R.
Voltage is electrical pressure: the push that drives current around a circuit. It is measured in volts, and it is the V in Ohm's law, V = I × R. A battery is the easiest picture — voltage is how hard it pushes, current is how much actually flows, and resistance is whatever gets in the way.
Because voltage is a push rather than a flow, it is measured across a component: a voltmeter is connected in parallel with the part being tested, while an ammeter sits in the circuit in series. Everyday values are a torch cell at 1.5 volts, a car battery at about 12, and a household outlet at 120 in the United States and 240 in much of the world.
Two consequences are worth holding. At a fixed resistance, more voltage gives more current, because the two rise together. Hold the voltage steady instead and adding resistance pushes the current down — which is why a short circuit is dangerous: the resistance collapses, so the current soars.
Taught in
Related terms
- resistance — Resistance is how much a material opposes the flow of current, measured in ohms. Rearranged from Ohm's law, R = V ÷ I: the more resistance, the less current flows.
Source: Official ASVAB — subtest descriptions (what each subtest asks) and the CAT-ASVAB scored-question counts (accessed 2026-09)