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**Current induced in a circuit due to magnetic flux.**

Find the current (as a function of time t) in the circuit consisting of a source of constant emf E and a choke coil of inductance L connected in series.

A closed circuit consists of a source of constant emf $E$ and a choke coil of inductance $L$ connected in series. The active resistance of the whole circuit is equal to $R$. At the moment $t=0$ the choke coil inductance was decreased abruptly $η$ times. Find the current in the circuit as a function of time $t$.

Instruction. During a stepwise change of inductance the total magnetic flux (flux linkage) remains constant.

Instruction. During a stepwise change of inductance the total magnetic flux (flux linkage) remains constant.