A circuit section AB contains a 1 H inductor, a 5 V cell and a 2 Ω resistor (see figure). Current i = 2 A flows from A to B and is increasing at di/dt = 1 A/s. Find Vₐ - Vᵦ. Image
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Question

A circuit section AB contains a 1 H inductor, a 5 V cell and a 2 Ω resistor (see figure). Current i = 2 A flows from A to B and is increasing at di/dt = 1 A/s. Find Vₐ − Vᵦ. Image

G1 Physics · Accepted Answer

Step 1: With current increasing at di/dt = +1 A/s, the inductor drop is L(di/dt) = 1 × 1 = 1 V. Step 2: Resistor drop is iR = 2 × 2 = 4 V. Step 3: Moving A → B through the source in the direction shown creates a drop of 5 V. Step 4: Kirchhoff voltage equation: Vₐ − Vᵦ = 1 + 5 + 4 = 10 V. Final answer: Vₐ − Vᵦ = 10 V, Option D.