What is the coil current 2ms after being connected to the supply if a coil of inductance 0.5H and resistance 500#Omega# is connected across a 250V DC supply? (The time constant T of the circuit is 1ms).

1 Answer
May 28, 2018

spanishplus.tripod.com/maths/CircuitExample1
For an LR Series circuit as shown in the figure above, the expression for the current #I# is given as

#I(t)=E/R(1-e^(-t/tau))#
where time constant #tau= L/R# and #E/R# represents the final steady state current in the circuit.

Inserting given values we get

#I_"(2 ms)"=250/500(1-e^(-2/1))#
#=>I_"(2 ms)"=0.43\ A#

.-.-.-.-.-.-

We can verify that #tau=0.5/500=0.001\ s#, as given