All Problems

Electromagnetic Induction. Maxwells Equations

Problem 3.317

A coil of inductance L=300mHL=300 \mathrm{mH} and resistance RR =140 mΩ=140 \mathrm{~m} \Omega is connected to a constant voltage source. How soon will the coil current reach η=50%\eta=50 \% of the steady-state value?

Reveal Answer
t=LRln(1η)=1.5 st=-\frac{L}{R} \ln (1-\eta)=1.5 \mathrm{~s}