What is Inside a Light Bulb?
Students create a complete circuit and light a large bulb using their materials. They examine and discuss the different parts of a bulb.
4-5 PS3E Electrical energy in circuits can be changed to other forms of energy, including light, heat, sound, and motion. Electric circuits require a complete loop through conducting materials in which an electric current can pass.
4-5 PS3B Energy can be transferred from one place to another.
4-5 PS3A Energy has many forms, such as heat, light, sound, motion, and electricity.
4-5 SYSD One defective part can cause a subsystem to malfunction, which in turn will affect the system as a whole.
- Students predict how many D-cell batteries it will take to light a household bulb.
- Students test how many batteries it takes to light a bulb and record observations.
- Students closely examine a bulb with the base removed in order to see the wires out the bottom and the side.
- Students determine that the wire must touch the bottom and side of the bulb in order to get the bulb to light.
- Using the bulb with the base removed helps students to better see the path the energy takes through the bulb, and why the side and base of the bulb must be touched.
- If possible use several bulbs with the bases removed.
|Students testing the effect of number
on the brightness of the bulb.
|Testing the bulb with the base removed.|
- In their science notebooks, have students record their prediction about how many batteries it will take to light the bulb.
- Have students record their observations in their science notebooks before or after they have had a turn to hold the bulb and wires in Procedure step 6; students can get off-task while waiting for their turn to hold the bulb.
- Photocopy the diagram of the household bulb (Figure 4-1) and white out the labels. Make copies and have students add the labels.
- As you are labeling the parts of the bulb, introduce systems and parts of the system. Discuss what would happen if you take out any of the parts (e.g. What will happen to the bulb system when we take out the filament? or What will happen to the bulb system if we take out the glass support?).
- This is also a good lesson to discuss the forms of energy students see in the system: electric energy, light energy, and heat energy (this is not in the teacher’s guide, but helps students better meet state science standards).
- In the Final Activities section, it might be helpful to have students finger trace the path the energy takes through the system.
- There are several ways to line up the batteries in this lesson. You can use a whiteboard tray, meter sticks placed parallel to each other, or foam pipe insulation that has been cut in half to create a groove. It is optimal to do this in an area where all students can easily see.
- Focus Question: How does energy flow through a bulb? How is a light bulb a system?
- An extension would be to have students record the forms of energy in their notebook.
- They can also use arrows to point to the location of the various forms of energy in the drawing of their bulb.
- This would be a good time to read books on Thomas Edison and other inventors who contributed to the study of electricity.
- The Electricity Kids Discover magazine has a time line with inventors and their contributions; there is also a section on Nikola Tesla.
Link to Worksheet:
- The Parts of a Bulb Worksheet has some additional scaffolding to help students label the parts of a bulb.