# Basic Circuits

An electrical circuit is like a NASCAR raceway.  The electrons (racecars) zip around the race loop (wire circuit) superfast to make stuff happen. Although you can’t see the electrons zipping around the circuit, you can see the effects: lighting up LEDs, sounding buzzers, clicking relays, etc.

There are many different electrical components that make the electrons react in different ways, such as resistors (limit current), capacitors (collect a charge), transistors (gate for electrons), relays (electricity itself activates a switch), diodes (one-way street for electrons), solenoids (electrical magnet), switches (stoplight for electrons), and more.  We’re going to use a combination diode-light-bulb (LED), buzzers, and motors in our circuits right now.

A CIRCUIT looks like a CIRCLE.  When you connect the batteries to the LED with wire and make a circle, the LED lights up.  If you break open the circle, electricity (current) doesn’t flow and the LED turns dark.

LED stands for “Light Emitting Diode”.  Diodes are one-way streets for electricity – they allow electrons to flow one way but not the other.

Remember when you scuffed along the carpet?  You gathered up an electric charge in your body.  That charge was static until you zapped someone else.  The movement of electric charge is called electric current, and is measured in amperes (A). When electric current passes through a material, it does it by electrical conduction. There are different kinds of conduction, such as metallic conduction, where electrons flow through a conductor (like metal) and electrolysis, where charged atoms (called ions) flow through liquids.

38 Responses to “Basic Circuits”
1. frauritsema says:

2. Aurora says:

No problem! When I started, I only had a battery, rubber bands and paperclips for my homemade “battery holder” and I made my own alligator electrical wires from aluminum foil and masking tape!

It’s hard to say what’s going on without actually *seeing* your experiment. You can send me images to my email at [email protected]

If you’re not sure of the minimum voltage requirement is for the LED, then you’ll want to hook up the batteries plus-to-minus, not plus-to-plus, so the voltage increases. You can check out the experiment on “Series and Parallel Circuits” to help guide you through when you should use each configuration. I recommend using those cheap “dollar store” type of batteries (listed in the shopping list) so your batteries have the least chance of exploding, because you’re right – if you hook them up the wrong way or with too many other batteries, you might have a problem.

3. frauritsema says:

Howdy,
We were working on this experiment and couldn’t get it to work (we didn’t have a battery case and use electrical tape instead and the LED might have too high a voltage). Anyway as we were troubleshooting I came across the idea of having the wire attached to the battery go across two ends of the same polarity (thus using four batteries). I wasn’t able to do it at my house because I’m not sure whether or not it would, for instance, cause the battery to explode, so I wanted to ask you what would happen if you had the metal part of the wire lay across two batteries? Would it increase the voltage?

Ps we ARE getting a battery case and Lowe voltage LEDs… we just got abit excited!

4. Michelle Palmer says:

Thank you for your quick response. That helped me a lot.

5. Aurora says:

Yes the wires inside are the same. They’re different colors so you can see them more easily when wiring as to which wire is going where. You need to power something with your wires and battery, like a light bulb. If you don’t, then the energy goes back into the battery, and it doesn’t have anywhere for it to go, so it keeps sending the electricity back to itself. You need the battery to drive something.

6. Michelle Palmer says:

Hi Aurora,

Are the wires inside the different colored alligator wires the same?

Just to see what happened I switched the red and black and the light bulb still lit up. Then I put a white one on and it still worked. So I was wondering if they are just color coded for us when hooking things up but is the wiring the same under the plastic.

Also, why would I blow the battery if I touched the two polars together but it doesn’t blow the batteries if I hook up a light bulb? What is going on inside the build that it isn’t the same thing as touching the wires together?

7. Aurora says:

Hi Jodi,

Wow – that’s cool about the long chain! 🙂

I’ve sent you a private email regarding the LED. For reference, you can get them from Radio Shack or Jameco.

8. Jodi Peveto says:

Hi Aurora! My girls tried this today and were very excited to make it work using a really, really, REALLY long paper clip chain!

The red led that came with our kit blew out within a few minutes of our trying the experiment. Could this have been something we did wrong? Also, is there an online supplier you recommend for these as they would like to have another red one. Thanks!

9. Tara Chapman says:

Do you include battery case?

10. Linda Elrod says:

this is very easy I did it in under a minute. 10 years old

11. Sophia Pitcher says:

Hi Aurora!

I understand that when you want to hook up an LED, you have to connect the positive side of the battery pack with the positive side of the LED and the negative side of the battery pack with the negative side of the LED. Why? What happens inside the LED? Does it work the same way with the buzzer? If not, why doesn’t it?

Thanks, Jasmin

12. Sophia Pitcher says:

Hi Aurora,

So, I’m trying to figure out how connecting the positive of a source with the positive of a load conducts electricity. I think that by connecting the two positives together creates a passage (or diode) for the electrons to zip through. If you connect a positive and a negative, it short circuits the whole connection, and the electrons can’t get through. Is this right?

Thanks, Isabel

13. E.T. says:

Thank you, multi -circuit, sound & light. Ezra T. from Houston . 8 yrs old

14. Aurora says:

Yes – that would be great!

15. Aurora says:

Yes, there are many simple circuits kits that are great – use it in addition with the extra content in this section and you’ll go far!

16. Lorelei Grecian says:

Do you want me to send you a pic?

17. Lorelei Grecian says:

Hi Aurora, I`m not sure if you know what this is but I have a brain box kit, it has parts that snap together! 😀
There is lights that turn on, and buzzers, and a clock……. Just wondering if I can use that instead.
Oh, and it has different ways to put it together not just 1. 🙂

18. Aurora says:

For Unit 10: Electricity, you’ll find Lesson 1 is Basic Circuits, and Lesson 2 is Robotics. Do you see the menu on the right with all the different lessons here on this page?

Hi Aurora,
I am seeing a shopping list for ‘Basic Electricity’, and ‘Circuits and Robotics’, but when I go to Unit 10: Electricity, the first lessons are about circuits. Are there any lessons on basic electricity, since there is a shopping list about it??
Thanks,
Krishnaya, age 9

20. Aurora says:

Wow – cool! And yes, the current went through my metal braces and light up a light bulb. 🙂

21. Sonya Fiebig says:

Dear Aurora,
I remembered somewhere you said that you hooked up your braces to an electric circuit when you were a kid, and so I thought I’d try that with my retainer, and it worked! I managed to make an LED light up (but not when it was in my mouth!)
Laura

22. Aurora says:

You know, we’ve had several requests for that very experiment. I’ll see if we can add it to our video shoot list shortly… I know that there’s been issues with it before because of the high voltage requirements, but maybe I can figure something safer out. More soon!

23. Deborah Gulick says:

We just watched the Electricity Discovery Pack DVD and made the robot using a thick slice of a foam pool noodle. The piece of foam included in the kit was not large enough, my son decided. We sliced one of the sides so it had a flat side to glue the battery pack and motor to.

Question: Are there instructions somewhere for how to take the graphite rods out of the used-up AA batteries and hook them together to make a spark? You mention it at the start of the DVD and want to try it.

Thanks!

24. Cyndi Harris says:

My son Michael was trying to find a way to connect the lighted Candy Canes that line each side of the sidewalk for the holidays so he decided to use the “alligator clips” to connect the plugs from one side to the other and then another strand of lights as the extension cord to the plug at the house.

25. Aurora says:

If you place too high of a voltage across a low-voltage LED, then it can certainly “break”. (You can tell because the insides go black.) You might want to try out a different LED – we gave you a few suggestions, but you can always try different LEDs – ones that are rated 2.2V and higher should work well. I am guessing you had either a 1.7V or 1.2V LED. Check the Unit 10 shopping list for LED recommendations, and check the voltage rating before you buy one.

26. Karen says:

We used a (quantity of) 2 AA batteries to power the led light, and two of the lights blew out. Should I have switched to one battery to power it?

27. Aurora says:

Hi Jessie,

LEDs last a lot longer than light bulbs, and will burn out if you run too much voltage or current through them. Only use one battery pack to power the LED at a time. Note that you might also have had a neon lamp included (which has much longer leads) and only lights up with a static charge (like a charged balloon) and not with a battery pack. I’ll send you a replacement.

28. Jessie Lin says:

Hi, Aurora,

We received from you the LED but it was only used once or twice and was dead now.
Fortunately I had the electronic bricks kits that I could find the replacement.
Can you share with us how to keep LED live longer? Thanks.

29. Aurora says:

Hi Phillip,

So glad you are into electronics! Unit 14 is going to be all about circuit boards and electronics, and over the summer we’re going to release release a set of videos that are just the kind you’re looking for. In the meantime, pick up a copy of this book: Getting Started in Electronics. It should point you in the right direction – it’s the one I had as a kid, and there really hasn’t been a better one published since. Keep an eye out for the experiments in Unit 14 and in the summer!

30. Deborah Andrews says:

Do you have any more ideas of advanced circuit experiments I could do? The ones in this unit were fairly simple, and I really like circuits and I’m into them. I have the book 50 CMOS IC projects and have been working on a few projects. They are really fun and right now I’m working on electrical organs using press switches. Do you have any suggestions on other books, etc. that I could use? Thanks for your help!

Philip Andrews
age 11

31. Aurora says:

Veronica Cable wrote: “Hi. We do not have any LED’s that have three legs or one that has two colors. Where can you get them?”

If you visit this post, you can click on the words “LED2” which take you right to the purchase link for the bi-color LED. Also check out LED3 and LED4 to see if those are ones you want to add to your collection. Enjoy!

32. Veronica Cable says:

Hi. We do not have any LED’s that have three legs or one that has two colors.
Where can you get them?

33. Aurora says:

Virginia Wrote:

Hi Aurora! NO! We are NOT feeling overwhelmed with the camp! It is awesome! 🙂 I had written to you to ask about all the parts for the electrical week, and I must say that we are very happy that we invested in those parts! My boys wanted to do every experiment, and we did! We spent 3 hours doing them, and they made up their own circuits, too!

The best part of the “learning” was when my youngest (almost 7) went to the pantry for lunch when we were done and exclaimed that he now knows how the light switch works — when it’s up, there’s a connection and the light comes on; and when it’s down, the connection is broken and the light goes off! I was thrilled!!! 🙂

I have to tell you, too, that my husband was teasingly doubtful that I could do this electrical stuff. Not only did I TELL him that I could do this with the boys, but I SHOWED him! We set up the “trip alarm” for when he came home from work, and it went off!! 🙂 🙂 The boys and I were jumping up and down in sheer delight!! Thanks for the fun ideas!! 🙂

We’re still searching for the pipe insulation … the ones at the local hardware store was too “floppy” for the marbles to roll through, so we’re off to check out another store for that … and another Radio Shack for the “bonus activity in electricity” because they didn’t have the transistor.

Thanks again for this great summer e-camp offer AND for posting the recording on the website, too, because we cannot make the phone calls. We are looking forward to this week’s e-camp!

34. Chris Criner says:

this player does not work well with my dsl connection- I am a MAC user

Chris Criner

35. Aurora says:

Jen Hubbard wrote: “Hi, We have the electricity kit that you provide and the aligator clips are not red and black — they are green, yellow, white and black. Is there a significance to the color?”

Good question – and the answer is NO, it makes no difference what color your alligator clip leads are.
However, the wires from your battery pack indicate the polarity – red is plus, black is minus. Enjoy!

36. Jen Hubbard says:

Hi,

We have the electricity kit that you provide and the aligator clips are not red and black — they are green, yellow, white and black. Is there a significance to the color?

37. Aurora says:

CoWefa Lyda wrote: “We have had a great start but when we hooked up the LED it would pop on and then off and burn out I checked to see if I got the right things from Radio Shack and I did. What have we done wrong? The buzzer works great. Thanks…”

If you place too high of a voltage across a low-voltage LED, then it can certainly “break”. (You can tell because the insides go black.) You might want to try out a different LED – we gave you a few suggestions, but you can always try different LEDs – ones that are rated 2.2V and higher should work well. I am guessing you had either a 1.7V or 1.2V LED. I’ll check our shopping list to see if there’s a low-V LED listed there.

38. CoWefa Lyda says:

We have had a great start but when we hooked up the LED it would pop on and then off and burn out I checked to see if I got the right things from Radio Shack and I did. What have we done wrong? The buzzer works great. Thanks