Chapter 21: Electric Current and DC Circuits Summary

Vocabulary flashcards covering key definitions, circuit rules, instruments, and units from the Chapter 21 summary.

Electric current

The flow of electric charge.

Ampere

The unit of electric current, where $1\,\text{A} = 1\,\text{C/s}$.

Battery

A device that uses chemical reactions to maintain a potential difference between its terminals.

emf

The potential difference between battery terminals in ideal conditions.

Direction of current

The direction in which positive charges would move.

Superconductor

A material whose electrical resistance drops suddenly to zero at the critical temperature, $T_C$.

Critical temperature ($T_C$)

The temperature at which the resistance of a superconductor drops suddenly to zero.

Kilowatt-hour

A unit of energy with the equivalent value of $1\,\text{kWh} = 3.6 \times 10^6\,\text{J}$.

Equivalent resistance for resistors in series

The total resistance calculated as $R_{\text{eq}} = R_1 + R_2 + R_3 + \dots = \sum R$.

Junction rule

The circuit rule stating that all current that enters a junction must also leave it.

Loop rule

The circuit rule stating that the algebraic sum of all potential charges around a closed loop must be zero.

Ammeter

An instrument that measures current, is connected in series, and should have a resistance that is as small as possible.

Voltmeter

An instrument that measures voltage, is connected in parallel, and should have a resistance that is as large as possible.