WEBVTT
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A resistor of resistance 1.8 kiloohms is connected across a battery of emf 5.0 volts.
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What is the current through the resistor?
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If we sketch this resistor as part of a circuit, we know it has a resistance ๐
of 1.8 kiloohms and that there is a potential difference of 5.0 volts across this resistor.
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Knowing all that, we want to solve for the current ๐ผ that runs through the resistor.
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Ohmโs law tells us that the current ๐ผ when we multiply it by the value of the resistor ๐
is equal to the potential difference across the resistor ๐.
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Looking back at our circuit, we see that the only place potential can drop is across the resistor.
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So therefore, that potential drop ๐ is equal simply to the potential supplied by the battery.
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So then, rearranging Ohmโs law, we can say that the current through this resistor is equal to the potential difference across it divided by its resistance.
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As we solve for this current, we want to be careful plugging in our value for the resistance ๐
.
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We make sure to include the fact that itโs 1.8 kiloohms of resistance so that resistance is 1.8 times 10 to the third ohms.
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Written in these units, weโre now ready to divide this resistance in the 5.0 volts to solve for ๐ผ.
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๐ผ is 2.8 milliamps or 2.8 thousands of an amp.
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Thatโs the current through this resistor.