A Level Physics Practice Exam

What characterizes an ohmic conductor?

1. A component with variable resistance

2. A component with constant resistance

3. A component that only allows AC current

4. A material with changing resistivity

The correct answer is: A component with constant resistance

An ohmic conductor is characterized by its ability to maintain a constant resistance regardless of the applied voltage or the current flowing through it. This relationship between voltage (V) and current (I) can be described by Ohm's Law, which states that V = I × R, where R represents resistance. In the case of an ohmic conductor, the resistance remains unchanged as the voltage or current levels vary, indicating that the material follows a linear relationship between these two quantities. This stability allows for predictable behavior in electrical circuits involving ohmic conductors, making them essential in various applications where consistent performance is required. Examples of ohmic conductors include metals like copper and aluminum, which exhibit minimal changes in resistance with temperature or current variations, thereby reinforcing their classification as ohmic. In contrast, components characterized by variable resistance or that exhibit changes in resistivity do not uphold the principles of ohmic conduction. Therefore, the defining feature of an ohmic conductor is its constant resistance.