voltage & current sensors

The scope for electrical measurement as obviously as big as the subject itself. Data logging systems tend to measure changes over time and that suits these sensors to measuring the life of a battery, induced emf as a magnet falls through a coil, discharge of a capacitor or surge current when switching on a lamp. There is great learning potential in seeing the way that the current through a bulb, resistor or diode changes as you slide a variable resistor. Likewise use them to see how the current and voltage in a circuit are related (see page 56). These uses are good, but using sensors as simple meters needs to be assessed carefully. It seems wise to look at the economics of replacing inexpensive meters with equipment specially designed for a computer. Otherwise these sensors connect into circuits just as their respective meters do. Check the instructions to see if you need to use a ‘common return’ – this means you connect the return lead of the current sensor to that of the voltage sensor.

Uses for voltage & current sensors

  • For current / potential difference measurements across resistors, a thermistor, a lamp or a diode.
  • Discharge of a battery or a lead-acid accumulator,
  • Surge current and the change in resistance when switching on a lamp.
  • Output voltage of an electronic oscillator.
  • Maximum power theory. Discharge of a capacitor.
  • Measuring the heating effect of a current and specific heat capacity.
  • Measuring the efficiency of a solar cell or an electric motor.
  • Induced emf resulting from a magnet moving through a coil.

My rating

I’ve rated these sensors but your assessment will be different. I give a score, out of five, for the sensor’s intrigue, interest, and learning potential. I also give a score for how often a science department might use it.

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