Question Video: Calculating the Current In a Circuit Containing a Cell and a Bulb | Nagwa Question Video: Calculating the Current In a Circuit Containing a Cell and a Bulb | Nagwa

# Question Video: Calculating the Current In a Circuit Containing a Cell and a Bulb Science • Third Year of Preparatory School

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The diagram shows a circuit consisting of a cell and a bulb. What is the current in the circuit?

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### Video Transcript

The diagram shows a circuit consisting of a cell and a bulb. What is the current in the circuit?

Here, we are given an electric circuit diagram with a cell that provides a potential difference and a bulb that has some resistance. We are asked to find the current that is in this circuit. To solve this question, we are going to need Ohm’s law. 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 current, we must make the current 𝐼 the subject of the equation. We can do this by dividing both sides of the equation by the resistance. This gives us the equation current 𝐼 is equal to the potential difference 𝑉 divided by the resistance 𝑅.

Let’s take a look at the units of this equation to familiarize ourselves with them. On the right-hand side of the equation, we have the unit of volts divided by the unit of ohms. And on the left-hand side, we have units of amperes, the units of current.

Now that we have the correct equation and the right units, we can put the given values in and solve it. Looking at the diagram, we see that the potential difference provided by the cell is 12 volts and the resistance of the bulb is three ohms. So our equation becomes the current in the circuit is equal to 12 volts divided by three ohms, which equals four amperes. Therefore, our final answer is the current 𝐼 equals four amperes.

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