Induction's Time-Space Tradeoff?
A physicist is designing a device to generate a magnetic field that induces an electromotive force (EMF) in a conductor attached to a rotating wheel. If the wheel completes a full rotation in 4 seconds and induces a maximum EMF of 12 V, at what distance from the center of the wheel would the conductor be placed to achieve a maximum EMF, assuming the magnetic field's strength is directly proportional to the distance?
1 Answer
📌 CONCEPT: Electromagnetic induction is the process by which a changing magnetic field induces an electromotive force (EMF) in a conductor, leading to the generation of an electric current.
📐 RULE / FORMULA: The induced EMF (ε) is directly proportional to the rate of change of the magnetic flux (dΦ/dt) and is given by the equation ε = -N(dΦ/dt) for N turns of the conductor.
💡 WORKED EXAMPLE: Let's assume the magnetic field's strength is directly proportional to the distance (r) from the center of the wheel, i.e., B ∝ 1/r. If the wheel completes a full rotation in 4 seconds and induces a maximum EMF of 12 V, we can find the distance where the conductor is placed. The rate of change of the magnetic flux is dΦ/dt = B × A × ω, where ω is the angular velocity. We can equate the induced EMF to 12 V and solve for the distance r.
⚠️ COMMON MISTAKE: Students often forget to consider the direction of the induced EMF and the changing magnetic field, which can lead to incorrect sign conventions and results.
16 Jul 26
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