Ohm's Law — FAQ
Frequently asked questions about Ohm's Law (V=IR).
Q1. What is the difference between voltage and current?
Voltage (V) is the electrical pressure or potential difference that drives current. Current (I) is the actual flow of charge. You need both — voltage drives current, and resistance limits it.
Q2. What is Ohm's Law used for?
Designing resistor networks, calculating safe fuse ratings, troubleshooting circuits, and sizing wires for electrical installations all rely on V = IR.
Q3. Does Ohm's Law apply to all materials?
Only to 'ohmic' materials where resistance stays constant regardless of voltage. Semiconductors, diodes, and LEDs are non-ohmic — their resistance changes with voltage.
Have more questions? Try the interactive calculator at /tools/ohms-law-visualizer