DIY Flashlight

About the Activity

In this activity, kids will learn about electrical energy using batteries and conductors as they create a battery-powered flashlight with an on/off switch.

Grades: 4-7
Topic: Electrical Engineering
Estimated Time: 1 Hour

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What You'll Need

Small piece of cardboard
Two large brass fasteners
Red and blue copper wire
1.8W lightbulb
2 D cell batteries
Electrical tape
Scissors
Wire strippers
Paper cup

Activity Steps

First, read the background information in the Explanation section below to understand how electrical currents work, and how this flashlight will work.
To begin the activity, take a piece of cardboard and trace a circle using the end of the opening cardboard paper towel roll. Cut this circle out.
Cut a small hole in the center of the cardboard circle and carefully place the
lightbulb through it.
Then take the cardboard paper towel roll and cut it lengthwise.
Using two brass fasteners, insert the first fastener inside the seam you just cut,
approximately 2 inches below the top edge of the cardboard. Then, place the paperclip around it and insert the second brass fastener close enough for the paperclip to reach it. (see image A for reference)
Next, take two pieces of individual copper wires and strip them so that approximately two inches of copper is exposed on both ends. Use different colors or label them ‘red’ and ‘blue’
Wrap the red wire around the first brass fastener and the blue wire around the second, and fold the fasteners over to secure the wire (see image B for reference).
Place the two D cell batteries on top of each other with the opposite terminals touching and secure them together tightly with electrical tape (see image C for reference).
Take the lightbulb in the cardboard circle and place it at the opening of the cardboard roll.
Lay the batteries flat on top of the brass fasteners and secure them in place with duct tape.
Make sure the positive battery terminal makes contact with the metal tip of the lightbulb.
Wrap the exposed red wire on the first fastener around the metal base of the lightbulb and secure it with electrical tape.
Now, it’s time to turn your flashlight on! Take the exposed blue wire connected to the second brass fastener and secure it to the bottom of the second battery using electrical tape. Once you connect the paperclip to the second fastener, the lightbulb should light up! To turn the lightbulb off, simply disconnect the paperclip.
Roll the cardboard roll together and secure using electrical tape. Flatten and cut the bottom off the paper cup to fit around the top to focus the light from the lightbulb. Secure using electrical tape.

Questions to Engage Youth

Why do the wires need to be stripped to make the lightbulb light up?
Why do the batteries need to touch the brass fasteners?
Is the circuit “open” or “closed when the paperclip touches both brass fasteners and the light is on?

Explanation

How Electrical Currents Work:
For electricity to work, electrons flow (electric current) must make a complete path, returning to the starting point. This path is called a circuit. What does the word circuit mean? The word circuit comes from the word circle since the electrons must travel in a circle to keep flowing.

The electrical current’s path of circuit is considered to be closed if electrons are allowed to flow completely through the cycle. An electric circuit is considered open if the electrical path is broken and electrons are not allowed to flow to complete the cycle.

How Batteries Work:
Batteries are a way to store electrical energy. In order to access that energy, you need to create a circuit using the battery’s direct current.

How This Flashlight Works:
The electrical current’s path of circuit is considered to be closed if electrons are allowed to flow completely through the cycle. An electric circuit is considered open if the electrical path is broken and electrons are not allowed to flow to complete the cycle. How batteries work: Batteries are a way to store electrical energy. In order to access that energy, you need to create a circuit using the battery’s direct current. How This Flashlight Works: When you taped the batteries together and attached the wires to the negative terminal and to the metal base of the lightbulb, you created a closed circuit that allowed energy to flow from the batteries into the lightbulb and light it. The brass fasteners act as conductors of electricity. When you touched the metal paperclip to both fasteners, this created another closed circuit to act as a switch. Finally, the paper cup helped to illuminate the lightbulb by diffusing the light it emits.

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Career Connections

If you enjoyed working with electricity and building a circuit, you might want to explore becoming an electrical engineer. Check out our interview with Martin Nelkie, an electrical engineer in South Dakota.