Chapter 20 - Electric Circuits Flashcards
What is the emf?
The electromotive force (emf) of a generator, such as a battery, is the maximum potential difference (in volts) that exists between the terminals of the generator.
What is the electric current?
The rate of flow of charge is called the electric current.
What is the SI unit of current?
C/s = A
Explain the difference between alternating and direct currents.
When the charges flow only in one direction around a circuit, the current is called direct current (dc). When the direction of charge flow changes from moment to moment, the current is known as alternating current (ac).
What is the conventional current?
Conventional current is the hypothetical flow of positive charges that would have the same effect in a circuit as the movement of negative charges that actually does occur.
(20.1)
What is the unit of resistance?
V/A = ohm
Explain current and voltage in series wiring.
When devices are connected in series, there is the same current through each device. Different voltage.
Explain current and voltage in parallel wiring.
When devices are connected in parallel, the same voltage is applied across each device. Different current.
Explain Kirchoff’s rules.
Kirchhoff’s junction rule states that the sum of the magnitudes of the currents directed into a junction equals the sum of the magnitudes of the currents directed out of the junction. Kirchhoff’s loop rule states that, around any closed-circuit loop, the sum of the potential drops equals the sum of the potential rises.
Explain the difference between an ammeter and a voltmeter.
An ammeter is an instrument that measures current and must be inserted into a circuit in such a way that the current passes directly through the ammeter. A voltmeter is an instrument for measuring the voltage between two points in a circuit. A voltmeter must be connected between the two points and is not inserted into a circuit as an ammeter is.
Explain charge in parallel capacitors.
Each contains a different charge.
