i=i0(1−eL/R−t)

=520(1−e0.01/5−t)
=4(1−e−500t)
now at t=∞
i∞=4
at t=40 s
i40=4(1−e−500×40)
=4(1−(e2)100001)=4(1−7.29100001)
i40i∞≈1 Slightly greater then one.
JEE Main 2020 — Physics Electromagnetism
An emf of 20V is applied at time t=0 to a circuit containing in series 10mH inductor and 5Ω resistor. The ratio of the currents at time t=∞ and at t=40s is close to: (Take e2=7.389 )
Held on 7 Jan 2020 · Verified 6 Jul 2026.
1.06
1.15
1.46
0.84
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