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Physical Effects of Electricity
11 questions By Tony R. Kuphaldt
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Question 10 of 11
What effect takes place when an electric current passes through a coil of wire, wrapped around an iron object such as a large-diameter bolt? Hint: place some small paperclips or other lightweight steel objects near the end of the bolt when energizing the coil. What is this phenomenon called?
Reveal answerThe phenomenon is known as electromagnetism.
Notes:This makes an excellent classroom demonstration, and students should immediately recognize some of the practical applications of this phenomenon.
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Question 11 of 11
When light strikes a phototube, an electric current is registered by the ammeter in this circuit:
What phenomenon is exhibited by the phototube in its function? What possible applications of this effect can you think of?
Reveal answerThis phenomenon is called the photoelectric effect. Incidentally, the mathematical expression of this effect earned Albert Einstein a Nobel Prize for Physics in the year 1921.
Notes:There are several features of the schematic diagram worthy of note:
- • High-voltage battery
- • Ammeter symbol (circle with letter Ä” inside)
- • Twin arrows designating light
Applications of the photoelectric effect are many and varied. Special versions of the basic phototube (called photomultiplier tubes) are able to detect extremely small impulses of light, enabling scientists to detect small light flashes from cosmic-ray events, among other optical phenomena.
