1.In 1780, Galvani, studying animal electricity, connected a long wire to a diss
ID: 1310070 • Letter: 1
Question
1.In 1780, Galvani, studying animal electricity, connected a long wire to a dissected frong 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 concluded that the electric "fluid" was already present in the frog's legs and that the metals merely served to release it, just as pipes can draw off water from tanks or reservoirs.Later it was explained that observed agitation was caused by an electric discharge due to contact of the two dissimilar metals, copper and iron.
2).AM radio ranges from 535 to 1705 kilohertz, whereas FM radio ranges in a higher spectrum from 88 to 108 megahertz.
AM Wavelength -- 600 - 200 m
FM Wavelength --5.55 m - 0.187 m
3). NO. because of different nature, Sound Waves require a medium where Light Waves do not require a medium.
4) Most of the Range
5). Because radio waves do not travel well through good electrical conductors like salt water.
6). Yes they can recieve, they will be much larger , and they cant detect the penny
7) A 15-watt light bulb emits 15 joules of energy each second.Thus, the number of 600-nanometers photons it emits each second is
number of photons =total energy emitted / energy emited per photon
=15 joule/3.31x10^?19 joule/photon
= 4.531x10^19 photons.
8). Flouresent Lamp as the energy per photon in lamp is less tha that in bulb
9). The bright yellow light emitted by a sodium vapor lamp consists of two emission lines at 589.0 nm and 589.6 nm.
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