Ohm’s law

Definition

Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points. It is mathematically expressed as $V = IR$, where $V$ is voltage, $I$ is current, and $R$ is resistance.

5 Must Know Facts For Your Next Test

1. Ohm's Law formula: $V = IR$.
2. The unit of resistance is ohms ($\Omega$).
3. Ohm's Law only applies to ohmic materials where the resistance remains constant regardless of voltage and current.
4. In a series circuit, total resistance equals the sum of individual resistances: $R_{total} = R_1 + R_2 + ... + R_n$.
5. In a parallel circuit, the reciprocal of the total resistance equals the sum of reciprocals of individual resistances: $\frac{1}{R_{total}} = \frac{1}{R_1} + \frac{1}{R_2} + ... + \frac{1}{R_n}$.

Review Questions

• What is the formula for Ohm's Law?
• How does Ohm's Law apply to series and parallel circuits?
• What are the units for voltage, current, and resistance?

Related terms

Voltage (V): The electrical potential difference between two points in a circuit. Measured in volts (V).

Current (I): The flow of electric charge through a conductor. Measured in amperes (A).

Resistance (R): A measure of how much a material opposes the flow of electric current. Measured in ohms ($\Omega$).