1. In 1780, Galvani, studying animal electricity, connected a long wire to a dis
ID: 1638294 • Letter: 1
Question
1. In 1780, Galvani, studying animal electricity, connected a long wire to a dissected frog via a nerve. He put another wire from the feet down a well, to ground it. As a thunderstorm approached, Galvani observed the legs twitched every time the lightning flashed. Explain.
2. What are the longest and shortest frequencies on an AM radio? What wavelengths do these imply? Do the same for FM radio. (HINT: you have to find a radio to check the dial--and don't forget the units!)
3. A light wave and a sound wave have almost the same wavelength. Can they therefore interfere?
4. What frequencies of electromagnetic radiation do you estimate would get into a metal birdcage? (Should you get your parrot an iPhone?)
5. Why doesn't your car radio work when you go through a tunnel under a river?
6. Suppose that intelligent life in other parts of the universe were able to perceive parts of the electromagnetic spectrum which are invisible to us. If such creatures used 1 to 2 meter radio waves, would they then be able to "see" our FM radio broadcasts? If they respond to radiation at those wavelengths, would you guess that these creatures were much larger or much smaller than us? Do you think they could they detect small objects, such as a penny?
7. Estimate the number of photons emitted per second by a 15 watt fluorescent lamp.
8. Which emits more photons per second: a 15 watt fluorescent lamp or a 15 watt incandescent bulb? [hint: which is warmer? What type of radiation do you associate with heat?]
9. Estimate the energy of the electronic transition seen in orange sodium vapor lamps.
Explanation / Answer
1. Galvani's experiment :
Connecting a long wire to a dissected frog via a nerve.Putting another wire from the feet down a well, to ground it. As thunderstorm approached , there was observation that legs were twitched every time the lightening flashed.
It proved not only that recently dead muscle tissue can respond to external electrical stumili , but the muscle and nerve cells possess an intrinsic electrical force that is responsible for muscle contractions and nerve conduction in living organism.
Hence it was important discovery of animal electricity by Galvani.
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