 Solution

ID: past-exam-of-the-physics-2-paper-of-the-university-of-oxford/2022/1/i/solution

L \frac{d I}{d t} + R I = 0.

The electric current through an ideal inductor remains continuous across a switch with no impulsive voltage. Thus

I (0^{+}) = I_{0}

I (t) = I_{0} e^{- Rt / L} (0 < t < Δ t) .

If the switch remains at A, the same result holds for every

t > 0

L / R

; the stored magnetic energy is dissipated by Joule heating.

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