Two coils having equal resistance but different inductances are connected in series, then the time constant of series combination will ______
a. sum of time constants of individual coils
b. average of time constant of individual coils
c. geometric mean of the time constants of individual coils
d. product of the time constants of individual coils...
please help me with the answer and tell me how...

Question

anonymous · Answer

time constant of rl circuit is r/l so time constants of individual circuits are l1/r and l2/r when they are connected in series the equivalent L=l1+l2 and r is r+r=2r hence time constant finally is (l1+l2)/2r which is average of both