Login
Copyright

Insulators and Conductors: Examples, Definitions & Qualities

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Voltage Sources: Energy Conversion and Examples

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
 Replay
Your next lesson will play in 10 seconds
  • 0:05 Conductors and Insulators
  • 2:56 Conductivity
  • 4:24 Conductors and…
  • 5:35 Lesson Summary
Add to Add to Add to

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Login or Sign up

Timeline
Autoplay
Autoplay
Create an account to start this course today
Try it free for 5 days!
Create An Account

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Jim Heald

Jim has taught undergraduate engineering courses and has a master's degree in mechanical engineering.

In this lesson, we'll explore the reasons that some materials conduct electrical energy with ease while others block it almost completely. We'll also talk about the property of conductivity and some everyday examples of insulators and conductors.

Conductors and Insulators

Back in the old days, if someone's house caught on fire, volunteers would rush to the scene and form a bucket brigade to put out the flames. If you think about it, you could say that the bucket brigade was 'conducting' water from the source to the fire. But, what if the volunteers stopped passing the water?

Well, we know one thing: the house would burn to the ground because it was effectively 'insulated' from the water! The bucket brigade scenario is actually very similar to why some materials act like electrical conductors and others act like electrical insulators. But, to find the actors in our electrical 'bucket brigade', we have to start at the atomic level.

Not all atoms are created equal. Some atoms don't hold on to their outer electrons very tightly. These are known as free electrons because they are literally free to roam around from atom to atom. Free electrons are the members of our electrical bucket brigade passing electrical energy from one electron to another.

Free electrons are free to roam from atom to atom.
Free Electrons

A material with many free electrons allows easy transfer of electrical energy and is therefore called a conductor. If we send an energetic electron into a conductor, it will impact a free electron, knocking it down the line until it hits another free electron. This sets up a chain reaction of impacts that conducts the electrical energy through the material.

A good way to think of it is like a group of balls spread out on a billiards table. Our energetic electron is like the cue ball being shot into the group and impacting one ball, which in turn knocks into another ball and so on down the line. Before you know it, the energy from the cue ball has been 'conducted' all the way to the other end of the table. The only real difference between billiard balls and electrons is that electrons conduct electrical energy at nearly the speed of light!

Insulators have very few free electrons and do not transfer electrical energy well.
Insulator

On the other end of the spectrum, there are atoms that hold on to their electrons very tightly. A material that contains these types of atoms has very few, if any, free electrons and does not transfer electrical energy well, if at all. This type of material is called an insulator.

If we send an energetic electron into an insulator, it effectively bounces off the atoms, unable to transfer its energy to the tightly bound electrons. It will keep bouncing around until it either frees another electron or until it simply runs out of energy!

Going back to our billiard table analogy, this is very similar to the cue ball simply bouncing off the sides of the table. Either it will hit another ball and transfer its energy, or it will just stop rolling because of friction.

Conductivity

The ability of a material to conduct electrical energy is known as its conductivity. Not surprisingly, materials that are good conductors have high conductivity, while materials that are good insulators have low conductivity. The conductivity of a material is dependent on the number of free electrons available, and this varies greatly between the different types of atoms. In general, the materials with the highest conductivities, or best conductors, are metals - but this doesn't mean that other materials aren't capable of conducting electricity. If that were true, no one would ever be in danger of getting electrocuted!

Examples of materials with low conductivities
Low Conductivity

On the other end of the spectrum, the materials with the lowest conductivities, or best insulators, are glass, ceramic, rubber and some plastics. Not all materials are classified as insulators or conductors, because in the real world, they don't do a particularly good job of either one.

One final note on conductivity: good electrical conductors are also good heat conductors. Electricity and heat are just two different forms of energy, but both rely on free electrons to transfer through the material. Sometimes it's easier to tell if a material would be a good conductor by using our sense of touch to see how well it conducts heat.

To unlock this lesson you must be a Study.com Member.
Create your account

Register for a free trial

Are you a student or a teacher?
I am a teacher
What is your educational goal?
 Back

Unlock Your Education

See for yourself why 10 million people use Study.com

Become a Study.com member and start learning now.
Become a Member  Back

Earning College Credit

Did you know… We have over 95 college courses that prepare you to earn credit by exam that is accepted by over 2,000 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it free for 5 days!
Create An Account
Support