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Static Electricity
9 questions By Tony R. Kuphaldt
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Question 7 of 9
Lightning is a spectacular example of naturally-generated static electricity. Explain how the vast static electric charges that cause lightning are formed by natural processes, and how those processes relate to the function of a device called a Van de Graaff generator.
Reveal answerThe static electric charges that cause lightning are generated by the action of wind and rain transporting electrons between clouds and earth, or between clouds. Particles of dust may also transport electrons in the same manner, which accounts for the spectacular discharges of lightning often seen during massive uprisings of dust, such as during volcanic eruptions.
In a similar manner, a Van de Graaff generator moves electrons from one point to another on a moving loop of fabric: a sort of conveyor belt for electrons.
Notes:Lighting provides a universal example of static electricity on a grand scale. The sheer awe of lightning is itself an attention-grabbing factor making it all the more appropriate for classroom discussion. When students’ collective attention and imagination are enthralled by fascinating subjects, learning is enhanced!
It goes without saying that the presence of a Van de Graaff generator in the laboratory is an excellent enhancement for this topic, as well.
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Question 8 of 9
A special kind of electric light known as a neon bulb is an excellent tool for demonstrating the presence of static electricity, and is easily obtained at most electronics supply shops:
When a large enough static electric charge is applied between the two wires of the neon bulb, the neon gas inside will “ionize” and produce a colored flash of light. Experiment with generating your own static electricity and then making the bulb flash. Hint: it may be easier to see the bulb’s flash if the room is dark.
What conditions produce the brightest flash from the bulb? What materials and techniques work best for producing strong static electric charges?
Reveal answerThis is definitely a question best answered by direct experimentation!
Notes:If it is difficult for students to obtain neon bulbs in your area, it might be a good idea to provide a few bulbs to experiment with when you give your students this worksheet. They are quite inexpensive and durable little devices.
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Question 9 of 9
If a neon bulb is used as a visual indicator of static electricity, it will be noticed that only one of the two metal electrodes inside the glass envelope glows upon discharge. Why is this? Why don’t both electrodes glow?
Reveal answerRemember that static electricity is an imbalance of electric charge between two objects. This imbalance has a definite polarity: one object is positive while the other is negative. This means that electrons rush in one direction when the two objects discharge through the path created by the neon gas inside the lamp. This unidirectional rush of electrons makes only one of the electrodes glow.
Notes:Of course, students will want to know: which type of charge makes the electrode glow, positive or negative? Don’t just give them the answer, but challenge them to devise an experiment whereby they could tell for certain which pole of the charge creates a glow. The answer to this question may have to wait until they learn about DC voltage sources like batteries, where the polarity of the voltage is known. However, even if they are yet unaware of DC voltage sources, it is a good exercise to have them imagine how they might test the polarity indication of a neon bulb (perhaps by postulating a source of static charge where the polarity is already known).
Someone clearly did an ill-advised search and replace turning “element” to “entry”, so this page mentions “entryary charge” instead of “elementary charge” and “the entry carbon” instead of “the element carbon”. Please fix this.
What is the math behind Q4? Showing the work might be a good idea.