Which term best describes a device that obeys Ohm's Law?

Which term best describes a device that obeys Ohm's Law?

• A. Ohmic
• B. Non-Ohmic
• C. LDR
• D. Filament bulb

Answer: (A)

Ohmic describes a device whose current is proportional to voltage with a constant resistance. When a component is Ohmic, the relation V = IR holds with R not changing as V or I vary, so plotting V against I gives a straight line through the origin. That’s why a fixed resistor or a metal conductor in which temperature changes don’t significantly affect resistance behaves Ohmically. Non-Ohmic devices don’t keep a constant resistance; the current and voltage aren’t in a fixed proportion. A filament bulb, for example, heats up as current increases, so its resistance rises and the V–I relationship is not a straight line. An LDR also changes resistance with light in a nonlinear way, so it doesn’t follow Ohm’s Law across its operating range.

Ohmic describes a device whose current is proportional to voltage with a constant resistance. When a component is Ohmic, the relation V = IR holds with R not changing as V or I vary, so plotting V against I gives a straight line through the origin. That’s why a fixed resistor or a metal conductor in which temperature changes don’t significantly affect resistance behaves Ohmically.

Non-Ohmic devices don’t keep a constant resistance; the current and voltage aren’t in a fixed proportion. A filament bulb, for example, heats up as current increases, so its resistance rises and the V–I relationship is not a straight line. An LDR also changes resistance with light in a nonlinear way, so it doesn’t follow Ohm’s Law across its operating range.