Ohm’s Law: Circuit Behavior, Material Properties, and Limits

All flashcards

What is static resistance for a nonlinear component?

The ratio $V/I$ at a particular operating point; it does not show that resistance is constant.

What does the Drude model use to explain electrical conduction?

Field-driven electron drift, together with scattering that redirects electron motion.

What is impedance in AC circuit analysis?

A generalized quantity that describes voltage–current relationships in circuits with reactive effects.

What is the hydraulic analogy for voltage difference?

A pressure difference that drives fluid flow through a restriction, analogous to voltage driving current.

How does temperature affect resistance measurements?

Heating can change a material’s resistivity and therefore its resistance.

Quiz questions

1. Which behavior characterizes an ohmic component over the operating range being considered?Answer: Its resistance is constant, and its $I$–$V$ graph is a straight line through the origin.
2. A nonlinear component has voltage $V$ and current $I$ at one operating point. What does the ratio $V/I$ give?Answer: Its static resistance at that operating point.
3. Which equation relates current density to electric field in a material?Answer: $\mathbf{J}=\sigma\mathbf{E}$
4. For a uniform conductor, which expression gives resistance in terms of resistivity $\rho$, length $\ell$, and area $A$?Answer: $R=\rho\ell/A$
5. Why is impedance used instead of resistance alone for circuits with capacitors or inductors?Answer: It accounts for reactive effects in the voltage–current relationship.