Ohm

Definition

An ohm is the unit of electrical resistance in the International System of Units (SI). It represents the resistance between two points of a conductor when a constant potential difference of one volt applied to these points produces a current of one ampere.

5 Must Know Facts For Your Next Test

1. The symbol for ohm is $\Omega$.
2. Ohm's Law states that $V = IR$, where $V$ is voltage, $I$ is current, and $R$ is resistance measured in ohms.
3. Resistors are components used in circuits to provide a specific amount of resistance.
4. The total resistance in a series circuit is the sum of individual resistances: $R_{total} = R_1 + R_2 + ... + R_n$.
5. In parallel circuits, the inverse of the total resistance is the sum of the inverses of individual resistances: $\frac{1}{R_{total}} = \frac{1}{R_1} + \frac{1}{R_2} + ... + \frac{1}{R_n}$.

Review Questions

• What does Ohm's Law state about voltage, current, and resistance?
• How do you calculate total resistance in a series circuit?
• What unit and symbol represent electrical resistance?

Related terms

Voltage: The electric potential difference between two points, measured in volts (V).

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

Resistor: A device used in electrical circuits to provide a specific amount of resistance.