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Does electron die?

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(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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RRITESH, what do you understand about electronics?

What is your background?

Why are you asking all these unrelated questions?

Do you speak English? (i.e. are you using google translate to read and post?)
 

BobK

Jan 5, 2010
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The current in an RC charging circuit decays exponentially. The time constant (RC) tells us how long it takes to charge up to 0.632 of the voltage it is charging from. Each time constant takes it this same proportion from the existing voltage to the final voltage. 5 is an arbitrary number used to express approximately how long it take to fully charge.

Since the equation for charging is:

V(t) = V0(1 - e^-(t / RC)

At 5 time RC it will be charged to

V0 (1 - e^-(5RC / RC) or V0 (1-e^-5) or 0.99326 V0

Bob
 

hevans1944

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Jun 21, 2012
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Or, if you have a particularly sensitive and high-resolution voltmeter to measure the capacitor voltage, you might give it ten time-constants to charge to 0.99995 times the charging voltage. For me, most of the time, that's more than enough time to consider the multiplier to be 1.00000 instead of the "real" value of 0.99995+. The only time I pick any nits about this is when charging a sample-and-hold capacitor for a 24-bit (or larger) analog-to-digital conversion. Most of the time five time constants or 0.99326+ is "close enuf" to 1.00000 for "guv'ment work." Your mileage (or kilometers) may be different.

Oh, my two centavos on electron life and health: Old electrons never die. Like old soldiers, they just fade away.

Hop
 

davenn

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thread closed ... the OP has been given a holiday ;)
 
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