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Old May 13th 2009, 05:06 AM   #1
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Smile kindly request

Maybe a little to easy but
Which one of these statements is true?
The frequency of a sine wave is determined by coil in the generator and turns the coil makes.
The frequency is determined by charge that completes one cycle leaving its original location and returning.
Period of em wave is determined by charged particle completing one cycle of oscillation
Two more question only
What is the deference between period and frequency?

If all flowing current have electromagnetic wave does it mean dc also have electromagnetic waves, how?
If similar questions have been answered plz refer.
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Old May 13th 2009, 10:07 AM   #2
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Period of em wave is determined by charged particle completing one cycle of oscillation.

What is the deference between period and frequency?
Period T is the time taken to complete one oscillation.
Frequency F is the number of oscillations per unit time , usually second.

F = 1/T

Suppose you are at a bus stop and the bus plying a particular route arrives every 15 minutes i.e. 1/4 hour. The time interval between buses is 15 min or 1/4 hr so that is the period . In one hour , there will be
1/(1/4) = 4 buses which is the frequency of that bus route.
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Old May 14th 2009, 09:34 AM   #3
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If all flowing current have electromagnetic wave, does dc current have it too?

thank you again physicsquest
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Old May 14th 2009, 10:07 AM   #4
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OOPS! Im sorry i missed that part.

An elecromagnetic wave is generated when charge is accelerated. In dc current there is only a steady flow of charge so no e.m wave is generated. However, a magnetic field is generated.
With ac however it is a different story as e.m. waves are generated. You might have heard an annoying low frequency hum when bad audio amplifiers are used, especially in public address systems.This is nothing but the e.m. waves (radiation) due to the 50/60 Hz present in the 230/110 V ac supply being picked up and amplified.
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Old May 14th 2009, 12:56 PM   #5
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No problem, thanx
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