Examkin

Question

Difficulty: MediumFundamentals of Electromagnetism and Induction

In an electromagnetic coil, increasing the rate at which electrical current changes produces a greater magnitude of induced counter-electromotive force (back-EMF) opposing the change.

Answer: Answer

Answer

True
The statement is true because the self-induced voltage (back-EMF) across an electromagnetic coil is directly proportional to the time rate of change of current (VL=LΔIΔtV_L = L \frac{\Delta I}{\Delta t}). As the current changes more rapidly, the expanding or collapsing magnetic flux induces a correspondingly larger opposing electromotive force.

Step-by-Step Solution

1
Identify the relationship between current flow through a coil and the resulting magnetic flux.
Current flowing through a coil generates a magnetic field proportional to the current magnitude; any change in current directly changes the magnetic flux linked with the coil.
Electromagnetic induction in an inductor depends directly on time-varying magnetic flux.
2
Apply Faraday's law of induction to determine the magnitude of the induced electromotive force.
The magnitude of the induced electromotive force is directly proportional to the time rate of change of magnetic flux (VL=LΔIΔtV_L = L \frac{\Delta I}{\Delta t}).
A higher rate of current change causes a faster rate of flux change, generating a greater induced voltage.
3
Apply Lenz's law to determine the direction and nature of the induced voltage.
The polarity of the induced voltage always opposes the change in current that produced it, acting as a counter-electromotive force (back-EMF).
Lenz's law establishes that the induced magnetic field always acts to oppose the change in magnetic flux.

Key Concept

Faraday's and Lenz's laws governing self-induction and counter-electromotive force (back-EMF) in electromagnetic coils.
Estimated Time:45s
Rate this question

Topics

Fundamentals of Electromagnetism and Induction

More questions from this topic