Lenz’s Law: States that the system is always going to be in opposition to change. Formally, the inducted current creates an induced field to oppose the change in Magnetic Flux.
Inductance is based on Lenz’s Law.
To find the direction of the induced magnetic field using Lenz’s Law, follow these steps:
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Determine the Change in Magnetic Flux:
- Identify the initial and final states of the magnetic field configuration.
- Calculate the change in magnetic flux (ΔΦΔΦ) using the formula: ΔΦ=B⋅A⋅cos(θ)ΔΦ=B⋅A⋅cos(θ), where BB is the magnetic field strength, AA is the area through which the magnetic field lines pass, and θθ is the angle between the magnetic field lines and the normal to the surface.
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Determine the Direction of the Change:
- Determine whether the change in magnetic flux is increasing or decreasing. If the magnetic field is increasing, the change is positive; if it’s decreasing, the change is negative.
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Apply Lenz’s Law:
- Lenz’s Law states that the induced magnetic field will always oppose the change in magnetic flux. This means the direction of the induced magnetic field will be such that it creates a magnetic field that opposes the change in the original magnetic field.
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Use the Right-Hand Rule:
- To determine the direction of the induced magnetic field, you can use the right-hand rule. Hold your right hand with your thumb pointed in the direction of the change in magnetic flux. Your fingers will then curl in the direction of the induced magnetic field.
Remember that the induced magnetic field is not always easy to calculate directly. Often, you’ll be more interested in understanding the effect it has on currents and magnetic fields in a circuit. For practical applications, it’s often enough to know that the induced field will oppose the change in magnetic flux.