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!