Difficulty: Easy
Correct Answer: electricity from magnetism
Explanation:
Introduction / Context:Electromagnetic induction is the backbone of electric power generation and many sensing technologies. Understanding the definition clarifies why rotating machinery, moving magnets, or time-varying fields can produce usable electrical power.
Given Data / Assumptions:
Concept / Approach:Faraday’s law states that a changing magnetic flux through a loop induces an electromotive force around the loop. Thus, motion of a conductor within a magnetic field or variation of the field over time generates an electrical response. This is succinctly “electricity from magnetism.”
Step-by-Step Solution:
Recognize that induced emf is proportional to −dΦ/dt.Create dΦ/dt by moving conductors or varying fields.Conclude that the phenomenon produces electrical energy/signals originating from magnetic effects.Verification / Alternative check:In generators, a coil rotates in a static magnetic field, changing flux → induced sinusoidal emf. In transformers, a time-varying primary current creates a changing flux in the core → induced voltage in the secondary (no mechanical motion required).
Why Other Options Are Wrong:
Common Pitfalls:Confusing electromagnetic induction with electromagnetic radiation or with the magnetic field produced by a current (the latter is the opposite direction of causality).
Final Answer:electricity from magnetism
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