Electricity and Magnetism

Current, Voltage, and Resistance

• Current is the flow of electric charge through a conductor, measured in amperes (A).
• Voltage is the potential difference that drives the current, measured in volts (V).
• Resistance is the opposition to the flow of current, measured in ohms (Ω).
• Ohm's law states that current is directly proportional to voltage and inversely proportional to resistance (I = V/R).
• Resistors, wires, and other components have a fixed resistance, while some, like light bulbs, have a variable resistance.
• Exam tip: Practice applying Ohm's law to calculate unknown values and understand the relationship between current, voltage, and resistance.