Can we solve this question by using KVL to derive characteristic equation and passive sign convention at t>0 rather than using derived formule. p.s. the response I(t) is underdamped.

I am having difficulty in assigning direction of voltage to inductor cuz going by passive sign convention for directions of inductor, I am getting a overdamped circuit.


  • \$\begingroup\$ The inductor induced emf, \$\small L\frac{di}{dt}\$, opposes the current arrow. \$\small \zeta =0.9\$, so just south of critically damped. \$\endgroup\$ – Chu Jun 22 at 13:40
  • \$\begingroup\$ It shouldn't matter which direction you chose for a voltage or current, as long as you are comfortable with negative values for voltage or current. It all works out in the end. \$\endgroup\$ – Elliot Alderson Jun 22 at 18:37
  • \$\begingroup\$ It will as I am getting my result as overdamped in place of having a underdamped circuit. \$\endgroup\$ – Derek Jun 22 at 20:24
  • \$\begingroup\$ as long as your convention is consistent, then it should not change the answer... the fact that you are getting a different answer should lead you to check the proper signs for all the other factors as well so they lead to the correct solution. \$\endgroup\$ – Juan Jun 24 at 7:32

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