Time Constant in RL RC Circuit
Just at the start of charging, potential difference across capacitor is zero, hence from (ii) putting vc = 0, we get
∴ initial rate of rise of voltage across the capacitor is
If this rate of rise were maintained, then time taken to reach voltage V would have been V + V/CR = CR. This time is known as time constant (λ) of the circuit.
Hence, time constant of an R-C circuit is defined as the;
Time during which voltage across capacitor would have reached its maximum value V had it maintained its initial rate of rise.
In equation given below
if t = λ, then
Hence,
Time constant may be defined as the time during which capacitor voltage actually rises to 0.632 of its final steady value.
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From the equation given below :
by putting t = λ, we get
Hence, the constant of a circuit is also;
The time during which the charging current falls to 0.37 of its initial maximum value (or falls by 0.632 of its initial value).
Read article – Capacitor
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