Each coulomb moving between two points of a circuit transfers 3 J. What is the voltage between the points?
A 9 V battery drives a bulb and a resistor in series, with a voltmeter across each component. The voltmeter across the bulb reads only 5.5 V. That is less than the battery supplies. What happened to the rest?
Here is the resistor's reading: its voltmeter shows 3.5 V.
Add the two readings: 5.5 V + 3.5 V = 9 V. The two readings add up to the battery's voltage.
Another circuit: a 12 V battery drives three resistors in series. Their voltmeters read 6.5 V, 3.0 V, and 2.5 V.
Add again: 6.5 V + 3.0 V + 2.5 V = 12 V. Again the readings add up to the source voltage.
A 7.5 V battery drives two resistors in series. Their voltmeters read 4.5 V and 3.0 V. Do the readings fit the series voltage rule?
One caution: voltage does not flow around the loop. Each reading is the energy that every coulomb transfers between the voltmeter's two points. The component voltages are shares of the source voltage.
So the bulb's missing 3.5 V was never missing. The resistor took it: 5.5 V + 3.5 V = 9 V.
A 6 V battery drives two resistors in series. Their voltmeters read 2.5 V and 3.5 V. Do the readings fit the series voltage rule?
Write down the rule:
In a series circuit, the component voltages add up to the source voltage.
Add the readings:
2.5 + 3.5 = 6.0
2.5 V + 3.5 V = 6 V, the source voltage. The readings fit the rule.
A 12 V battery drives three bulbs in series. Which set of bulb voltages is possible?
Amir says voltage flows around the circuit and gets used up on the way. Is Amir correct?
A 9 V battery drives a bulb, a buzzer, and a motor in series. Which statement about the three component voltages is correct?
A 15 V supply drives three resistors in series. Which set of resistor voltages is possible?
In a series circuit, which quantity do the component voltages add up to?