Ohm

Definition

An ohm is the unit of electrical resistance in the International System of Units (SI). It is symbolized by the Greek letter omega (Ω).

5 Must Know Facts For Your Next Test

1. One ohm is defined as the resistance between two points where one volt of potential difference causes a current of one ampere.
2. Ohm's Law, $V = IR$, connects voltage (V), current (I), and resistance (R) in a linear relationship.
3. Resistivity ($\rho$) and length ($L$) impact resistance, with $R = \frac{ \rho L }{A}$, where $A$ is the cross-sectional area.
4. Materials with low resistivity have lower resistance and are better conductors, while high resistivity materials have higher resistance.
5. Temperature can affect resistance; for most conductors, resistance increases with temperature.

Review Questions

• What is the unit of electrical resistance?
• How does Ohm's Law relate voltage, current, and resistance?
• How do resistivity and length affect the total resistance in a conductor?

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).

Resistivity:

A material property that describes how strongly it resists current flow, symbolized by $\rho$ and measured in ohm-meters (Ω⋅m).