Video Transcript
Which of the following devices can
be used to measure electric current? (A) A newton meter, (B) an ammeter,
(C) an ohmmeter, (D) a potentiometer, (E) a voltmeter.
Most of the devices listed are used
to measure a piece of data, as implied by the “meter” part of each name. It is important to know exactly
what each device measures so that you will know how to use the data that you
collect. It is very helpful to know the
units of measurement that you would assign to each piece of data, since that will
help identify the device that you will need to use.
This question is asking which
device might be used to measure electric current. Let’s start by identifying what
unit you might use for data collected from each device.
First, let’s look at the newton
meter. There is a clue in the name of the
device that can tell us what is measured. Recall that the unit for force is
newtons, named after Isaac Newton. Therefore, it makes sense that a
newton meter would measure an amount of force.
Next, let’s think about an
ammeter. This device is a little bit
trickier since it uses an abbreviated version of the unit in the name. However, we can take the part of
the word “am” and assume that it stands for amps or amperes. This is the unit for electric
current. So we can presume that an ammeter
measures electric current.
Next, we have an ohmmeter. The name of this device also
contains the units for the quantity it measures, ohm. Recall that ohm is the unit for
electrical resistance. So this device measures the amount
of resistance.
Next, we have a bit of a tricky
device, the potentiometer. This is the only device on this
list that does not contain the units of measurement in the name. This device can be found in an
electric circuit, and it does measure electric potential, volts, but in a unique
way. It uses varying amounts of
resistance to control the amount of voltage at a point in the circuit.
Finally, let’s look at the
voltmeter. The name of this device contains
the unit volt, which is the unit for electric potential. So this device measures electric
potential.
Now that we’ve identified what each
device measures, we can identify (B), an ammeter, as the correct answer.
