the available source of charge that pushes a charge through a circuit is?

Question

A. Voltage
B. Resistance
C. Direct Current
D. alternating current

Answer 1

Voltage

Answer 2

Voltage V = IR; where I is the current in amps and R is the wire resistance in ohms. Rewritten, we have I = V/R, which is math talk for saying "apply a voltage V to a resistance R" and you'll get a current I.

The current is formed of free electrons in the wire. That is, these are electrons that are not attached to the atoms of the material the wire is made of...like copper atoms for example.

What many, if not most, people fail to understand is that these free electrons move at a fairly slow rate through a wire. This physical movement is called electron drift. [See source.]

The reason current (energy) seems to travel instantaneously from the switch to the light, motor, A/C, or whatever, is because the signal (the electron wave/phase) travels at light speed through the wire. Light speed in wire is slower than in a vacuum, but it's still in the hundreds of thousands of km per second. That's why your lights seem to go on right away even though the free electrons are drifting about .024 cm/sec or so depending on the wire and voltage.

Answer 3

Frankly, non of the suggested answers in the multiple choice section make sense at all. Voltage cannot be a "source of charge", and neither an all other choices.

However, if the circuit is driven by a battery, that battery would indeed be a source of charge that is injected into the cicuit. Likewise, if the circuit is connected to the power grid, that grid would be the source of charge.

Answer 4

Voltage, or electromotive force (EMF)