Skip to content
kuazaraKuazara
Log in

Science · Electric circuits

Conductors and insulators

Why is the inside of a cable metal and the outside plastic? Use a simple test circuit to find out which materials conduct electricity and which do not, and learn how this protects you from electric shock.

  • 15 min
  • 1 simulation
  • Mini quiz

Updated:

Preview

The question

Look closely at your charging cable. Inside it there are thin, shiny, copper-coloured wires; the outside is covered in soft plastic. Why isn't the whole cable made of metal, or the whole cable made of plastic? Why are the handles of electricians' screwdrivers covered in thick plastic?

Try it yourself

No account needed: change the values and check your answer. Some simulations ask for a prediction before they start; it doesn't matter whether it's right or wrong.

Number line

How many objects are conductors?

Move the marker to the number of conducting objects and submit your answer.

Prediction

Predict first

What do you think mostly decides whether an object lights the bulb in the test circuit?

It doesn’t matter whether you’re right; the simulation opens once you choose.

Share: Share to Google Classroom (opens in a new tab)

Embed the simulation on your site

Paste this code into the HTML of your blog or school site. Visitors try the simulation without an account; no progress is saved.

The embedded page sets no cookies and does no tracking. A small link back to Kuazara sits underneath.

Log in to continue

The rest of the lesson is waiting for you, with a mini quiz. Creating an account is free.

Start for freeLog in

Frequently asked

4 questions

Why do metals conduct electricity?

In metals, some electrons are not tightly held by their atoms and can move freely through the material. An electric current is the orderly movement of these charges. Insulators such as plastic and glass have almost no such free charges, so current does not flow.

If pure water is an insulator, why is it dangerous to touch electrical devices with wet hands?

Pure water conducts very poorly, but tap water, sweat and sea water contain dissolved substances, so they do conduct. Wet hands make it easier for current to pass into your body. Always dry your hands well before touching a socket, plug or electrical device.

Why don't birds get a shock when they sit on power lines?

When a bird sits on a single wire, there is no path through its body to another wire or to the ground, so no significant current flows through it. If it touches two wires, or a wire and a pole, at the same time, it gets a shock. You stand on the ground, so a path would form; never go near power lines or fallen cables.

If air is an insulator, how does lightning happen?

Air is normally a good insulator; that is why sparks do not jump between the two holes of a socket. But at extremely high voltages, such as between a cloud and the ground, air becomes a conductor and lightning forms. So even an insulator has its limits.