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 and inversely proportional to the resistance between them. Mathematically, it is represented as $I = \frac{V}{R}$ where $I$ is current, $V$ is voltage, and $R$ is resistance.

5 Must Know Facts For Your Next Test

1. Ohm's Law only applies to ohmic materials, which have a constant resistance regardless of the applied voltage.
2. The SI unit for resistance is the ohm ($\Omega$).
3. Increasing the resistance in a circuit decreases the current if the voltage remains constant.
4. Ohm's Law can be rearranged to solve for voltage ($V = IR$) or resistance ($R = \frac{V}{I}$).
5. Non-ohmic materials do not follow Ohm's Law; their V-I relationship is non-linear.

Review Questions

• What is the formula represented by Ohm’s Law?
• If you double the resistance in a circuit while keeping the voltage constant, what happens to the current?
• Does Ohm's Law apply to all types of materials? Explain your answer.

Related terms

Current:

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

Voltage:

The electrical potential difference between two points, measured in volts (V).

Resistance:

The opposition to the flow of electric current, causing electrical energy to be converted into heat, measured in ohms ($\Omega$).