magnetic needle

American  

noun

1. a slender magnetized steel rod that, when adjusted to swing in a horizontal plane, as in a compass, indicates the direction of the earth's magnetic fields or the approximate position of north and south.

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magnetic needle British  

noun

1. a slender magnetized rod used in certain instruments, such as the magnetic compass, for indicating the direction of a magnetic field

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Etymology

Origin of magnetic needle

First recorded in 1840–50

Example Sentences

After analyzing the field strength frozen in the tiny magnetic needles, they found that its intensity had already jumped to 70% of present values, they reported at the AGU meeting.

From Science Magazine

The researchers looked at samples of plagioclase and clinopyroxene from eastern Quebec, Canada and found that they contain magnetic needles approximately 50 to 100 nanometers in size, surprising the researchers.

From Fox News

Finding the magnetoreceptors responsible for triggering these neurons has been like looking for a magnetic needle in a haystack.

From Science Magazine

On this as on the previous voyage, Hudson made some observations on the inclination or “dip” of the magnetic needle, and he is probably the first Englishman who had done so.

From Project Gutenberg

Faraday showed that a rotating disk of non-magnetic metal would draw after it in similar rotation a magnetic needle suspended over it, and even a heavy magnet.

From Project Gutenberg