At a point in a desk fan's wire, 1.2 C of charge pass each second. Enter the current, in amperes.
A small flashlight battery is labeled 1.5 V. A car battery is labeled 12 V. The number is not an amount of charge, and it is not a current. So what does it mean?
Earlier in this course you saw the volt: 1 V is 1 J of energy for each coulomb of charge, and potential difference and voltage name the same quantity. This lesson puts the volt to work between two points of a circuit.
Take the car battery: 12 V between its two terminals.
A 12 V battery gives each coulomb that passes through it 12 J of energy.
When two coulombs pass, the battery gives 24 J. When half a coulomb passes, it gives 6 J. The number of volts states the energy per coulomb.
The same idea works between any two points of a circuit, not just across a battery.
Across a lamp, the voltage states how much energy each coulomb transfers to the lamp as it passes through.
What does the voltage between two points of a circuit state?
One caution: voltage does not flow around the circuit. Current flows; voltage is a difference, measured between two points.
A 9.0 V battery drives a current through a small fan. How much energy does the battery transfer to each coulomb that passes through it?
Write down the fact:
The voltage states the energy transferred per coulomb.
Apply it:
9.0 V means 9.0 J for each coulomb.
Each coulomb gains 9.0 J.
A 6.0 V battery powers a bike light. Enter the energy, in joules, the battery gives each coulomb that passes through it.
Between two points of a circuit, each coulomb that moves transfers 5 J. What is the voltage between the two points?
Write down the fact:
The voltage between two points is the energy transferred per coulomb moving between them.
Read the value:
5 J for each coulomb is 5 V.
The voltage between the points is 5 V.
Each coulomb moving between two points of a circuit transfers 3 J. What is the voltage between the points?
The battery labels, read correctly: the flashlight battery gives each coulomb 1.5 J; the car battery gives each coulomb 12 J.
A 4.5 V battery pack powers a bike light. Which statement is correct?
A wall outlet supplies 120 V between its two contacts. What does the 120 state?
Imani says a battery's voltage flows around the loop and gets used up as it goes. Which statement about voltage is correct?