Have you ever encountered the question: “Which of the following magnets works by utilizing the Earth’s magnetic field?”
If you have, the correct answer is a Magnetic Needle, like the one you find in a compass.
But why is that? Let’s break it down in simple terms so you fully understand the science behind it.
Table of Contents
Understanding the Two Main Types of Magnets
First, it’s important to know the two main categories of magnets:
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Permanent Magnets: These are magnets that have their own persistent magnetic field. A common example is a bar magnet holding papers on your fridge.
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Temporary Magnets (Electromagnets): These only become magnetic when an electric current flows through them. Turn off the power, and the magnetism disappears. A scrap yard crane that lifts cars is a perfect example.
So, How Does a Magnetic Needle Work?
A magnetic needle is a permanent magnet that is very lightweight and free to rotate. This is the key!
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Even though the needle has its own magnetic field, it is very small and light.
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When it’s allowed to move freely (like in a compass), the Earth’s massive magnetic field influences it and causes the needle to pivot.
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The needle’s north pole will always point towards the Earth’s geomagnetic South Pole (which is located near the geographic North Pole).
So, the conclusion is: A magnetic needle works by utilizing the Earth’s magnetic field because it uses this planetary field as a guide to point direction.
Why Aren’t the Other Magnets Correct?
Let’s quickly see why the other options are not the right answer:
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A Horseshoe Magnet (U-Shaped Magnet): This is a strong permanent magnet. Its own magnetic field is far too dominant to be practically used for detecting the Earth’s weaker field. It’s designed for lifting objects, not for navigation.
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A Bar Magnet in an Electric Motor: Electric motors operate on electromagnetism—the interaction between magnetic fields and electric current. They do not rely on the Earth’s magnetic field to function.
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A Cylindrical Magnet on a Fridge Door: Like a bar magnet, this is a strong permanent magnet. Its sole purpose is to create an attractive force to hold the door shut. It does not “use” the Earth’s magnetic field.
The Bottom Line
So, to answer the question: “Which of the following magnets works by utilizing the Earth’s magnetic field?”
The correct answer is the Magnetic Needle (Compass).
It is the only one specifically designed to interact with and be guided by our planet’s magnetic field. We hope this explanation makes it crystal clear