Video Transcript
The diagram shows two resistors
connected in parallel to a cell. If the potential difference across
the three-ohm resistor is 18 volts, what is the potential difference across the
six-ohm resistor?
In this question, we’re considering
a circuit with two resistors connected in parallel. Since we know the potential
difference across one resistor and we want to find the potential difference across
the other, we should recall that the potential difference across each branch of a
parallel circuit is the same. Since here the three-ohm resistor
is connected in parallel with the six-ohm resistor, the potential difference across
the six-ohm resistor must be the same as the potential difference across the
three-ohm resistor. That is, the reading on voltmeter
𝑉 two equals that on voltmeter 𝑉 one.
In the question, we are given 18
volts as the value of the potential difference across the three-ohm resistor. This means that the six-ohm
resistor must also have a potential difference of 18 volts across it. Therefore, we know that the
potential difference across the six-ohm resistor is 18 volts.
