Video Transcript
The diagram shows a circuit
consisting of a cell and a resistor. The cell provides a potential
difference of nine volts and the current in the circuit is 1.5 amperes. What is the resistance of the
resistor?
In this question, we are given an
electric circuit diagram with a cell and resistor. The cell is providing a potential
difference of nine volts. And we are also told the current in
the circuit is 1.5 amperes. We are asked to find the unknown
resistance of the resistor labeled as 𝑅. And we will use Ohm’s law to find
this value. Recall that Ohm’s law states, for
two points in a circuit, the potential difference across the points equals the
current between the points multiplied by the resistance of the object between the
points.
Ohm’s law can be written as an
equation, where 𝑉 stands for the potential difference across the resistor, 𝐼
stands for the current in the resistor, and 𝑅 stands for the resistance of the
resistor. To find the resistance, we must
make 𝑅 the subject of the equation. We can do this by dividing both
sides of the equation by the current. This gives us the equation
resistance 𝑅 is equal to the potential difference divided by the current.
Before putting in the given values,
it’s always a good idea to take a look at the units we are working with. In this equation, we have the unit
of volts divided by the unit of amperes on the right-hand side, and that is equal to
the unit of ohms on the left-hand side. Now let’s go ahead and put in the
given values and solve this equation. The resistance of the resistor is
equal to nine volts divided by 1.5 amperes, which is equal to six ohms. So our final answer is the
resistance 𝑅 equals six ohms.
