Video Transcript
Each of the following diagrams
shows an electric circuit. Which one shows how the ammeter
must be connected to the circuit in order to measure the current in the circuit?
Before answering the question,
let’s review some facts about ammeters and currents in electric circuits.
We know that an ammeter is used to
measure the electric current in a wire. For an ammeter to measure the
current through a component, the ammeter must be on the same path as the
current. This means that ammeters are always
connected in series with the current they’re measuring and not in parallel. Remember, connecting a component in
series means that it is inserted directly into the path of the main circuit, while
connecting a component in parallel means that the component is on a separate
path.
Also remember that for an electric
circuit to have a current in it, the circuit must be a closed loop without any
breaks in the wires. For example, is there any current
in the single wire on the left? Only one end of the wire is
connected to the circuit, so there is nowhere for the current to go if it travels
through this wire. Therefore, we can assume that there
is no current in this wire.
Now that we have reviewed some
information about circuits and ammeters, we can rule out any of the circuits that do
not have the ammeter connected in series and in a closed loop. That leaves answer (C) as the
correct answer.
