Work done by power supply to maintain a constant current

Thread starter mymodded
Start date May 4, 2024
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Power supply Work done

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SUMMARY

The discussion centers on the relationship between the work done by a power supply and the change in potential energy in a coil within a magnetic field. It asserts that to maintain a constant current, the work done by the power supply must counteract the change in potential energy, leading to the equation W = -ΔU. The confusion arises from the answer guide omitting the negative sign, which is essential for accurately representing the energy dynamics in this context.

PREREQUISITES

Understanding of electromagnetic theory
Familiarity with the principles of electric circuits
Knowledge of potential energy in magnetic fields
Basic grasp of work-energy principles

NEXT STEPS

Study the concept of work-energy theorem in electromagnetism
Explore the role of inductance in maintaining current
Learn about the effects of magnetic fields on electric circuits
Investigate the mathematical derivation of W = -ΔU in electromagnetic systems

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Electrical engineers, physics students, and anyone involved in the design and analysis of electromagnetic systems will benefit from this discussion.

May 4, 2024

mymodded

Homework Statement: A coil with N turns and area A, carrying a constant current, i, flips in an external magnetic field, ##\overrightarrow{B_{ext}}##, so that its dipole moment switches from opposition to the field to alignment with the field. During this process, induction produces a potential difference that tends to reduce the current in the coil. Calculate the work done by the coil's power supply to maintain the constant current.

Relevant Equations: $$U = NiAB\sin(\Theta)$$

Since we want the current to stay constant, the change in potential energy that's caused by the coil flipping in the magnetic field should be "undone" by the work done by the power supply, so shouldn't ##W = -\Delta U## ? the answer guide did it without the negative sign, so I'm wondering if the negative sign should be included or not and because we don't really want to add more potential energy.