# Using voltmeters to measure voltage

• JustinLiang
In summary, the student needs to connect a voltmeter to measure the potential difference between X and W in order to measure the potential difference across the parallel resistors in the given circuit. X and Y are at the same potential due to a shorting wire between them, so measuring between them would result in a reading of 0V. The combination of all lines shown can be considered as shorting wires with no voltage drop along them. Additionally, measuring between Y and W would also work as they are at different potentials.

## Homework Statement

A student needs to connect a voltmeter to measure the potential difference across the parallel
resistors in the circuit shown below
Question 28

None

## The Attempt at a Solution

I thought it would be X and Y, in fact I also think it would be none of them because they don't seem to be in parellel. Can someone please explain why it is X and W?

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JustinLiang said:

## Homework Statement

A student needs to connect a voltmeter to measure the potential difference across the parallel
resistors in the circuit shown below
Question 28

None

## The Attempt at a Solution

I thought it would be X and Y, in fact I also think it would be none of them because they don't seem to be in parellel. Can someone please explain why it is X and W?

Welcome to the PF.

X and Y are at the same potential (voltage) -- there is just a shorting wire between them, so you would read 0V.

If you measure between X and W, you are measuring the voltage difference between the right and left side of the parallel combination of two resistors. Think of all the lines shown as shorting (zero resistance) wires, with no voltage drop along them.

Last edited by a moderator:
berkeman said:
Welcome to the PF.

X and Y are at the same potential (voltage) -- there is just a shorting wire between them, so you would read 0V.

If you measure between X and W, you are measuring the voltage difference between the right and left side of the parallel combination of two resistors. Think of all the lines shown as shorting (zero resistance) wires, with no voltage drop along them.

OHHHH ok thanks haha. What about Y and W, even though it is not an option would that work as well?

JustinLiang said:
OHHHH ok thanks haha. What about Y and W, even though it is not an option would that work as well?

Yep, Y and W would work as well. Good job!