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Electricity and Circuits
Quick questions on Voltage, resistance and Ohm's law: N(A)-Level Physics electricity
4short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is voltage?Show answer
Voltage (also called potential difference) is the energy given to each unit of charge by the source, or the energy transferred by each unit of charge in a component. It is what pushes the current around a circuit. Voltage is measured in volts () using a voltmeter connected across (in parallel with) a component.
What is resistance?Show answer
Resistance is how much a component opposes the flow of current. A high resistance lets only a small current through for a given voltage. Resistance is measured in ohms ().
What is ohm's law?Show answer
Ohm's law states that the current through a metal conductor is directly proportional to the voltage across it, provided its temperature stays constant. This gives the equation:
What is electrical power?Show answer
Electrical power is the rate at which a component transfers electrical energy, for example into heat and light. It is given by:
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