Work done by power supply to maintain a constant current

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Start date May 4, 2024
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Power supply Work done

In summary, the work done by a power supply to maintain a constant current involves delivering energy to a circuit in a way that compensates for any resistive losses. This ensures that the current remains steady, despite fluctuations in load or resistance. The power supply must continuously adjust its output voltage to provide the necessary energy, calculated as the product of current and voltage, to uphold the desired current level over time. This process is crucial for the proper functioning of electronic devices and circuits requiring stable operation.

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.

FAQ: Work done by power supply to maintain a constant current

1. What is the definition of work done by a power supply?

The work done by a power supply is defined as the energy transferred by the power supply to maintain a certain current in a circuit over a period of time. It is calculated as the product of voltage, current, and time, expressed in joules (J).

2. How is the work done by a power supply calculated?

The work done (W) by a power supply can be calculated using the formula W = V × I × t, where V is the voltage across the power supply, I is the current flowing through the circuit, and t is the time duration for which the current is maintained.

3. Does the work done change if the current is constant?

If the current is constant, the work done by the power supply will depend on the voltage and the duration of time the current is maintained. Therefore, while the current remains constant, changes in voltage or time will affect the total work done.

4. What role does resistance play in the work done by a power supply?

Resistance in a circuit affects the amount of current that flows for a given voltage (Ohm's Law: V = I × R). Higher resistance will result in less current for the same voltage, thereby affecting the work done. If the power supply is maintaining a constant current, it must adjust its voltage according to the resistance in the circuit to do so.

5. Can work done by a power supply be negative?

In the context of electrical circuits, work done by a power supply is typically considered positive when it is supplying energy to the circuit. However, if we consider the perspective of energy loss (such as in the case of energy being dissipated as heat in resistive components), one might think of the work done against the power supply as negative, but conventionally, the work done by the power supply is treated as positive.