Frequently Asked Questions
What is Ohm's Law?
V = I × R: voltage equals current times resistance. Power adds: P = V × I = I²R = V²/R. These four quantities are the foundation of DC circuit analysis.
What are the units?
Voltage in volts (V), current in amperes (A), resistance in ohms (Ω), power in watts (W). 1 V across 1 Ω carries 1 A and dissipates 1 W.
Does Ohm's Law apply to all components?
Only to ohmic (linear) components like resistors. Diodes, transistors, and incandescent bulbs are non-ohmic - their resistance changes with voltage or temperature.
How do I find the right resistor for an LED?
R = (V_supply − V_LED) / I_LED. For a 5 V supply, a red LED (2 V, 20 mA): R = (5 − 2)/0.02 = 150 Ω.
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