To measure the current through a motor, how is the ammeter connected?
The ammeter sat in the path, counting flow. But voltage is not a flow. It is a difference between two points, and measuring it needs a different hookup.
In earlier grades you saw components connected in series (one after another, on one path) or in parallel (side by side, on separate paths). Reading a voltage needs the second way.
The voltage across a lamp is measured between two points: the lamp's two ends.
An instrument that reads a voltage is called a voltmeter. On a diagram, the voltmeter is drawn as a circle marked V.
To measure the voltage across the lamp, the voltmeter's two leads connect to the lamp's two ends.
That places the voltmeter in parallel with the lamp: side by side with it, sharing its two connection points.
Wired like this, the voltmeter compares the lamp's two ends. It reads the energy transferred per coulomb between them: the lamp's voltage.
To measure the voltage across a motor, how is the voltmeter connected?
The same hookup works for any component: to read a battery's voltage, the two leads go on the battery's two terminals.
Now the wrong hookup. Wired in series, into the lamp's path, the voltmeter's leads no longer sit at the lamp's two ends.
A series-wired voltmeter compares the wrong pair of points, so its reading is not the lamp's voltage.
A technician wants the voltage across a heater element. Where do the voltmeter's leads go?
Write down the rule:
A voltmeter measures the voltage across a component and connects in parallel with it.
Apply it:
One lead goes on each end of the heater element.
The voltmeter's two leads connect to the heater element's two ends, in parallel with it.
A voltmeter's two leads are connected to the two ends of a heater element. What does the voltmeter read?
A voltmeter is connected across a buzzer, and it reads 3 V. What does that 3 V state?
Write down what the voltmeter compares:
The voltmeter compares the buzzer's two ends.
Read the number:
Its reading is the energy transferred per coulomb moving between them.
Each coulomb passing through the buzzer transfers 3 J: the voltage across the buzzer is 3 V.
Luis wires a voltmeter into a lamp's path, in series. Why is his reading not the lamp's voltage?
The two instruments, side by side: an ammeter goes in the path, in series; a voltmeter goes across the component, in parallel.
Which hookup reads the voltage across a pump motor?
Which pairing of meter and hookup is correct?
A voltmeter is connected across a buzzer. Which two points does it compare?