By Siobhan Fairgreaves

Last time, in D for Detectors, we looked at some of the applications of physics that you might encounter during your day. In this post, we’re going to find out more about something I can guarantee you use almost every day- electricity!

Far from simply being a piece of tack on your ‘cool’ uncle’s shelf, the plasma lamp is one of the best ways to see electron flow  in action

A reliable source of electricity is something we could easily take for granted, but how does it actually work? Well, surprise surprise, it all comes back to our friend- the humble atom. More specifically, electricity is the flow of electrons – remember them?

Electrons are the tiny negatively charged subatomic particles which whizz around the outside of the nucleus. In some materials, such as copper, the outer electrons break off quite easily and their movement through the material (a copper wire for example) creates an electric current.

Of course, not all materials can conduct electricity. I’m sure you remember the experiment in school where you tried to complete a circuit with different materials- they didn’t all work. Rubber, for example, holds onto its electrons pretty tightly so they can’t easily flow. This means rubber can’t conduct electricity.

Now back to that circuit experiment you may have tried. Your copper wires alone aren’t enough to light the bulb- you also need a source of power, like a battery.  The battery is a source of “pushing power” to move the electrons along. The official name for this is the electromotive force (EMF) but it’s more commonly known as voltage.

Ah, the good old Mexican current… at least that’s what it’s called among scientists who advocate Mexican wave-particle duality | Image: Martin Thomas

One way of thinking about electricity is a bit like a Mexican wave in a stadium. It usually takes a few people acting together to get it started- that’s the battery, and then the wave (or energy) transfers through each person and onto the next. The moving wave is a bit like the moving electrons.

Time for a fun fact now- did you know that the band AC/DC can actually teach us more about electricity? Their name came from seeing a symbol on their sisters’ electric sewing machine. This symbol stood for Alternating Current/Direct Current and meant that the machine could work with either type or electrical current.

“I’m on the hiiiiiiighwaay to… oh yeah, I’m periodically changing direction, so I guess I’m not really going anywhere” – an electron in an AC power line

Direct Current is best explained by the Mexican wave analogy used above. All the electrons move in the same direction. This type of current is used in toys and small gadgets. Larger machines tend to require Alternating Current.

The electrons forming an Alternating Current reverse direction 50 to 60 times a second. It’s a bit difficult to imagine how that could create a current but remember it’s all about transfer of energy. The battery still provides the initial push but these electrons don’t run in a straight line, they run on the spot instead. It doesn’t work in quite the same way but, just like Direct Current, still requires loose electrons and they still need energy.

See you next time for a convenient start of summer post- F for Flying!

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s