A LITTLE LIGHTBULB MOMENT
Physics: electricity, waves and optics
Ohm’s law links voltage, current, and resistance
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Voltage is the push; resistance is the clog
The idea behind the cue
Ohm’s law states that current is proportional to voltage and inversely proportional to resistance: V = IR. For a fixed resistance, increasing voltage increases current. For a fixed voltage, increasing resistance decreases current. This is a core relationship for simple resistive circuits.
Practice this flashcard →Make it memorable
Short & simple
Voltage is the push; resistance is the clog
Acronym
VCR — Vampire Cupcakes Roll.
Story
A parade truck rolls down a street. When the mayor turns up the street’s push, more trucks move each minute. When cones stack up, the convoy crawls even if the push stays the same.
Connect the pieces
- V (Vampire) → Voltage: The electric push (potential difference) that drives charge through a circuit; for a fixed resistance, higher voltage means higher current.
- C (Cupcakes) → Current: The flow rate of electric charge; it increases when voltage increases if resistance stays the same.
- R (Roll) → Resistance: The opposition to charge flow; for a fixed voltage, higher resistance means lower current. In ohmic materials, V = IR.
- Vampire · Voltage: The electric push (potential difference) that drives charge through a circuit; for a fixed resistance, higher voltage means higher current.
- Cupcakes · Current: The flow rate of electric charge; it increases when voltage increases if resistance stays the same.
- Roll · Resistance: The opposition to charge flow; for a fixed voltage, higher resistance means lower current. In ohmic materials, V = IR.
Know the limits
Applies to ohmic conductors over ranges where resistance is approximately constant; many devices are nonlinear.
Further reading · OpenStax science textbooks ↗Check your understanding
A resistor has a fixed resistance. If the voltage across it doubles, what happens to the current through it?
A. It halves
B. It stays the same
C. It quadruples
D. It doubles
Reveal explanation
It doubles
By V = IR, with R constant, current is directly proportional to voltage. Doubling voltage doubles current.