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ASVAB · Magnetism and Electromagnetism

What is produced when electric current flows through a coil of wire?

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Correct answer

A magnetic field, creating an electromagnet

  1. A Nothing
  2. B A permanent magnet that never weakens
  3. C Only heat
  4. D A magnetic field, creating an electromagnet

Why this is the answer

When electric current flows through a coil of wire, it produces a magnetic field, creating an electromagnet. The strength of the magnetic field can be increased by adding more turns of wire, increasing the current, or placing an iron core inside the coil. Unlike a permanent magnet, an electromagnet's field can be turned on and off by controlling the current, which makes electromagnets useful in motors, relays, speakers, and many devices. This relationship between electricity and magnetism (electromagnetism) is a key topic on the Electronics subtest.
Source: ASVAB Electronics Information — Electromagnetism

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About this topic: Magnetism and Electromagnetism

Magnetism and electromagnetism questions cover how current creates a magnetic field, how a changing field induces current, and the devices built on those effects — motors, generators, relays and transformers. This is one of 4 Electronics Information questions on magnetism and electromagnetism, each with a full explanation on a single study page.

New to this exam? Our ASVAB exam guide explains the format, scoring, and how to prepare.

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