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!
