How we measure electricity

How we measure electricity


Hello again, I’m Doctor Bruce Warrington,
Australia’s Chief Metrologist. Today I want to talk about how we measure
electricity. The basic electrical unit in our international
system is the ampere, the unit of current or how much charge is flowing each second.
It’s closely connected to the volt, for voltage, and the ohm, for resistance, because
these three physical quantities are related through a famous equation called Ohm’s Law.
All three units are named after scientists who helped develop our understanding of electricity.
Today our best electrical standards are quantum standards. It turns out that under just the
right conditions, voltage and resistance are quantised – they have a kind of ruler of
fixed steps, where the step size is set by fundamental constants and is always the same.
We can scale these measurements up and down. Going from billionths of a volt – to millions
of volts! This facility at the National Measurement Institute makes lightning and tests components
of our electricity supply grid to make sure they’re safe.
I think it’s fascinating that the electricity we use every day is ultimately measured using
the quantum properties of nature – and I hope you don’t find that too shocking!

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