Question

A closed circuit consits of a source of constant and `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 abrupty `eta` times. FInd the current in the circuit as a function of time `t`.
A. zero
B. E/R
C. `(nE)/(R)`
D. `(E)/(nR)`

Answer 1

Correct Answer - C
Due to charge in inductance , magnetic flux remains constant .
but ,`phi` = li= constant
`L_(1)l_(1) = L_(2)l_(2)`
`Here, L_(2) = (L_(1))/(n) and l_(1) = (E)/(R) therefore L_(2) = (L_(1)l_(1))/(L_(2)) = (nE)/(R)`