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  • Hello. This is 6 Minute English from

  • BBC Learning English. I'm Neil.

  • And I'm Georgina.

  • Now, Georgina, what do you know

  • about AC DC?

  • You mean the Australian rock'n'roll band?

  • Well, their 1979 hit 'Highway

  • to Hell' stayed

  • at No.1 for eleven weeks...

  • No, no, no - not that AC DC, Georgina!

  • I'm not talking rock music here,

  • I'm talking electrical

  • currents - alternating current - AC,

  • and direct current - DC, the two ways

  • in which electricity flows.

  • Oh, I see. No, I don't know anything

  • about that ACDC!

  • Well, don't worry because in today's

  • programme we'll be finding out

  • some quirky facts about

  • electricity - how it differs across the world

  • and why some countries

  • have more complicated

  • electrical systems than others.

  • Hmmm, I have noticed that when

  • I travel to another country

  • I need a converter plug to

  • connect my laptop. Is that something

  • to do with AC DC?

  • Yes, it could be. Of course, electricity

  • itself doesn't change from

  • country to country.

  • No. It's an invisible, natural force at work

  • in everything from lightning storms to the

  • electrical sparks firing our brains.

  • But although it happens naturally,

  • one scientist was credited with

  • discovering electricity.

  • Who? That's my quiz question - who

  • discovered electricity? Was it:

  • a) Thomas Edison, b) Alexander Graham

  • Bell, or c) Benjamin Franklin?

  • I'm not a qualified electrician myself, Neil,

  • but I'll say c) Benjamin Franklin.

  • OK. Well one person who definitely is

  • a qualified electrician is BBC presenter

  • Gareth Mitchell.

  • So when BBC Radio 4's 'Science Stories'

  • sent him to meet electricity

  • expert Keith Bell,

  • the conversation was, shall

  • we say, sparky.

  • Standard frequency in the US is 60 hertz,

  • actually I think in the US on the mainland

  • US, main continent, there are three

  • different synchronous areas.

  • So although it's around

  • 60 hertz, at any moment in time these

  • three different areas, because

  • they're not connected

  • to each other, will be going at a slightly

  • different frequency. There are

  • bigger differences

  • elsewhere. So in Japan for example,

  • I think one of the main islands is

  • at 60 hertz and

  • the other half of Japan is at 50 hertz.

  • That's a bit of a pickle!

  • Generally speaking, frequency means how

  • often something repeats.

  • In the case of electrical

  • currents, frequency is the number of

  • times an electrical wave repeats

  • a positive-to-negative cycle.

  • It's measured in hertz (Hz).

  • In the US power is at 60 hertz and

  • in the UK it's around 50 hertz.

  • So the US and UK are not in the same

  • synchronous area - not occurring

  • together at the same

  • time and rate, or in this case, frequency.

  • Which means that to safely use a British

  • electrical device in America,

  • I need to convert the power

  • supply. If not it won't work or

  • even worse, it could break.

  • And a broken laptop could leave you

  • in a bit of a pickle - an informal

  • expression meaning

  • a difficult situation with no obvious

  • answer. Here's Gareth and Keith again

  • talking about

  • more differences.

  • I'm pretty sure when I go to the United

  • States, my electric toothbrush

  • doesn't charge up at

  • 60 hertz - 110 volts, but my laptop still

  • works. Maybe you have

  • no comment, Keith, but

  • I'm just saying... one of these anomalies

  • that I seem to have found.

  • So, I'm not sure about the electric

  • toothbrush but I know a lot

  • of our power supplies for

  • laptops and stuff are solid state

  • you know - they've got electronics

  • in that do all the

  • conversion for you, so basically it ends up

  • with a DC supply into the machine itself.

  • So there's a little converter in there

  • and it's designed so it doesn't care

  • what frequency

  • the AC input is.

  • Gareth noticed that in the United States

  • his toothbrush doesn't always

  • fully charge up -

  • get the power needed to make it work.

  • Electric toothbrushes which don't fully

  • charge and differences between

  • electrical frequencies

  • are good examples of anomalies - things

  • which are different from what

  • is usual or expected.

  • But with modern technology these

  • anomalies are becoming less

  • and less commonplace. For

  • example, computer companies have

  • started making laptops with

  • solid state electronics - electronics

  • using semiconductors which have no

  • moving parts and can automatically

  • convert different

  • electrical currents.

  • Meaning I can use my laptop to google

  • the answer to your quiz question!

  • Ah, yes. I asked you which scientist was

  • credited with discovering electricity.

  • And you said?

  • c) Benjamin Franklin - and I already know

  • I'm right because I googled it on my solid

  • state laptop! To show that lightning was

  • electricity, Franklin attached

  • a metal key to a kite and

  • flew it during a thunderstorm. The key

  • conducted electricity and

  • gave him a shock!

  • Hmm, not an experiment I recommend

  • trying at home! Today we've been

  • talking about anomalies

  • - or unexpected differences in electrical

  • currents between countries.

  • Electrical currents are measured

  • in frequencies - the number of times a

  • wave repeats a positive-to-negative

  • cycle. These can be different

  • if two countries are not synchronous -

  • occurring at the same

  • rate, for example Britain and

  • the United States.

  • Different frequencies may mean your

  • electrical devices like your laptop,

  • phone and toothbrush

  • won't properly charge up - get the power

  • to function, in other countries.

  • And having a phone with no power could

  • leave you in a bit of a pickle -

  • a difficult situation.

  • Fortunately many modern devices use

  • solid state electronics -

  • non-moving semiconductors

  • inside the machine which automatically

  • convert the electrical current.

  • So you'll never miss another edition

  • of 6 Minute English again!

  • That's all for today. See you soon at

  • BBC Learning English for

  • more interesting topics

  • and related vocabulary. Bye for now!

  • Bye!

Hello. This is 6 Minute English from