Of course, you don’t have to have a scope to do this. You can use a voltmeter and an ammeter, but it is very straightforward if you have a four-channel scope with a pair of current probes.

But imagine a voltmeter so small that it can slip into a living cell and measure the voltage across the outer layer of structures known as organelles. That’s what a team of researchers at the ...

Voltage is measured in volts, V, with a voltmeter. Voltmeters are always connected in parallel. This is because it is measuring the difference in energy between the two points it is connected across.