A Level Physics Practice Exam

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Study for the A Level Physics Exam. Our quiz features flashcards and multiple choice questions, each with hints and explanations. Prepare thoroughly!

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How can the resistance of a thermistor be calculated?

  1. By measuring voltage with a voltmeter only

  2. By dividing voltage by current

  3. By measuring temperature and using a chart

  4. By using an external power supply

The correct answer is: By dividing voltage by current

The resistance of a thermistor can be calculated by dividing the voltage across it by the current flowing through it, as per Ohm's law (V = IR). This relationship holds true for any resistor, including thermistors, which are temperature-dependent resistors. By accurately measuring the voltage and the current, you can determine the resistance at a specific temperature. Measuring voltage with a voltmeter only does not provide enough information to calculate resistance, as it lacks the current measurement needed to apply Ohm's law. Using a chart based on temperature may provide resistance values for specific temperatures, but it involves looking up values rather than calculating them directly. While using an external power supply can create the necessary conditions for measurements, it does not directly contribute to the calculation of resistance without further measurements.

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