How to Build a Circuit Using Light Bulbs

Building circuits is a fun and easy way to learn the basics of electricity. The light bulbs provide immediate visual confirmation that your circuit is working. The sections below will explain how to build both a series circuit and a parallel circuit using light bulbs.

Things You'll Need

• 2 D-cell batteries
• 2 1-D battery holders
• 3 SPST (single pole single throw) knife switches
• 4 Mini #48, 1.5V light bulbs
• 4 Mini sockets
• 10 Test leads with alligator clip ends
• 2 Small wooden blocks
• 2 2 inch screws

Instructions

Series Circuit

1. Insert your battery into the battery holder. Clip a test lead to one of the battery contacts and a second test lead to the other contact.

2. Attach one of the leads from the battery to a contact on the first light socket. Attach a third test lead to the other contact of the first socket, and a contact on the second socket. Attach a fourth test lead to the other contact of the second socket.

3. Screw light bulbs into the two sockets.

4. Connect the lead from the second socket to one contact on the switch. Be sure the switch is in the open (off) position. Now connect the lead from the battery to the other contact on the switch.

5. Flip the switch and admire your handiwork.

Parallel Circuit

1. Insert your battery into the holder. Attach one test lead to each contact on the holder.

2. Screw one screw into each wood block, leaving about half of the screw sticking out to use as a post. Attach one lead from the battery to each screw post.

3. Attach two more leads to each screw post, resulting in each post having three alligator clips on it.

4. Using the leads from the first screw post, attach each lead to a contact of one switch.

5. Using the leads from the second screw post, attach each lead to a contact of one light socket. Screw in the light bulbs for each socket.

6. Be sure your switches are open (off) before proceeding. Connect each switch to a socket using a test lead. Your parallel circuit is now complete.

7. Flip one or both switches and see your circuit at work. The parallel circuit works in such a way that it can power both light bulbs, or one or the other, depending on which switches you turn on. Visit the links in the Resources to learn more about these circuits and their uses.

Tips & Warnings

• These activities can be done without the switches, but the switches add a degree of safety to the exercise.

• Series circuits are designed with one path for the electricity to follow, so that all parts of the circuit must be functional. If any part is broken or disconnected, the flow of electricity is stopped and the circuit will not work. These are typically used when you will need to be alerted to a parts failure such as a light bulb going out.

• Parallel circuits are designed with multiple paths for the electricity to follow. As long as the parts on at least one path of the circuit are functional, the circuit will work. The wiring of your house is designed in parallel circuits for this reason. Otherwise, if you had one light bulb out, nothing in your house would work until you replaced the bulb.

• Never touch exposed wiring with bare hands when it is "live," or has electricity flowing through it. If in doubt, do not touch.

Resources

• Electrical Supplies