In this Instructable, I made a workbench where students can play around and learn about circuits and connect lights in different ways. I made this workbench for grade 3 and 4. You can start by throwing some questions on kids.
* Have you ever wondered how current flows in a circuit ?
* How the light bulb glows at your home ?
* If a fan of your room goes off, why does all the lights don't go off ?
* Why sometimes bulb of your home is brighter and sometimes it is Dim?
Well...working on this workbench will answer all the questions. So lets begin.
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Step 1: SOME THEORETICAL UNDERSTANDING
Electricity is simply flow of current/electrons through a conductor. Current needs a path to follow, which we call circuits. The circuit can be open and closed. A close circuit has a complete path for current to flow. A circuit which has broken path is called an open circuit.
There are two ways through which we can connect lights :
SERIES CIRCUIT: Lights connected one after another is called series circuit. Any circuit that has one path to follow is series circuit. The current has to travel through each part of the circuit. If resistors are connected in the same way, the total resistance increases thus preventing the flow of current. According to ohms law, if voltalge is constant and resistance increases, the current in the circuit also decreases. So if we add more and more lights in series, the lights will be dimmer than the last.
PARALLEL CIRCUIT: Any circuit that has two or more paths or multiple paths to follow is called a parallel circuit. When we add resistors in parallel, total resistance decreases. Each light have its own direct path to voltage source. As we add more lights in parallel, the total resistance decreases, and current increases, increasing the brightness of lights.
Step 2: MATERIALS REQUIRED
1. One Wooden Board
3. Nose Plier
4. Eight Alligator clips
5. Four Washers
6. Eleven Nails
7. Four Screws
8. Two AA Batteries
9. Three lights
10. Jumper Wires
Step 3: BUILD
1. Take a wooden block of approximately 15*9 Inches.
2. Using scale start marking dots for battery space.
3. On the dots marked, start hammering the nails. The one nail in between the batteries will let you choose whether to use one battery or two to power the light bulbs. Point the negative ends of the batteries (the flat ends) towards the left.
4. Place two AA batteries(1.5 Volts each) inside the nail space, separated by a nail.
5. Using marker, mark four lines (below batteries) where screws and alligator clip will go.
6. Place washer below the screw on the lines marked and start hammering the screw.
7. I have used the needle-nose plier to bend the two small tabs at the ends of alligator clip outward. Place two alligator clips below the washer from the ends so that they position in opposite direction parallel to the wooden board. Screw it tightly using a cordless drill until clips are firmly held between washers and wooden board.
8. Repeat step 6 and 7 to screw rest of the screws and washers on the remaining marking.
9. Use a marker or pencil to number the alligator clips 1 through 8 to help you keep track of your observations.
10. Secure the numbering using a transparent tape.
Voila... We are done with the Workbench. Lets start working on it.
Step 4: OPEN AND CLOSED CIRCUIT
Use two alligator-clip leads(Red and Black) to connect the nails at the ends of the batteries to clips 2 and 3. Electrons come out of the negative end of the left battery to begin their journey through the circuit. They travel through clips 2 and 1, the wire, clips 5 and 6, the bulb, clips 7 and 8, the wire, clips 4 and 3, and back into the positive end of the right battery. This path is called a complete electrical circuit. What happens to the bulb when you make the final connection? Is it shining? If yes then it is a closed circuit.
Remove one of the jumper wire from clip 1 without replacing the bulb. What happens to the bulb? Is it still glowing? If no, then it is an open circuit as the current has no path to flow through the circuit.
Observation: Move one of the alligator clips from a nail at the end of the battery holder to the nail between the batteries. What did you observe?
Step 5: SERIES CIRCUIT
Keep a bulb between clips 6 and 7. Replace the wire between clips 1 and 5 with a second bulb. Then replace the wire between clip 4 and 8 with the third bulb. All three bulbs should light and glow with approximately the same brightness. How does the brightness of these bulbs compare to the brightness of the single bulb in the initial setup?
Observation: Remove one of the bulbs from the circuit without replacing it with a wire. What happens to the other two bulbs? Do they still glow?
Step 6: PARALLEL CIRCUIT
Connect one of the alligator clip leads from the negative end of the battery holder to clip 1. Connect bulbs between clips 1 and 5, between clips 2 and 6 and between 3 and 7. Connect clips 2 and 3 and 6 and 7 via jumper wire. Connect the lead from the other end (positive) of the battery holder to clip 8. What happens? How it is different from series connection? How does the brightness of the single bulb compare with the brightness of each of the two bulbs?
Observation: How does the behavior of the two bulbs differ from that of the three bulbs that were connected differently? Remove one of the bulbs. What happens now ?
Step 7: STUDENTS HAVING FUN
After introduction of the basic concepts, I let the students work on this workbench and explore it. They really had fun working on this.
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Participated in the
Classroom Science Contest