magnetic needle
Definition
A magnetic needle is a small magnet that is free to rotate on a point. It is used in compasses to point north.
The magnetic needle is made of a material that is easily magnetized, such as iron or steel. The needle is then placed in a liquid, such as alcohol or oil so that it can rotate freely.
The Earth has a magnetic field, and the magnetic needle is attracted to the north and south poles of the Earth's magnetic field. The north pole of the magnetic needle is attracted to the south pole of the Earth's magnetic field, and the south pole of the magnetic needle is attracted to the north pole of the Earth's magnetic field. This is why the magnetic needle always points north.
The magnetic needle is also affected by other magnetic fields, such as those created by nearby magnets or electrical currents. This is why compasses can sometimes be inaccurate near large metal objects or power lines.
Magnetic needles are a simple but important tool that has been used for centuries to navigate. They are also used in a variety of other applications, such as gyroscopes and magnetic resonance imaging (MRI) machines.
How can the word be used?
The scientist magnetized the needle to make it point north.
Different forms of the word
Noun: A small, magnetized needle that is free to pivot on a point and is used to indicate direction, especially in a compass.
Adjective: Describing something that is made of or contains a magnetic needle. For example, you could say "a magnetic needle compass" or "a magnetic needle field".
Verb: To magnetize a needle. For example, you could say "The scientist magnetized the needle" or "The current magnetized the needle".
Etymology
The word "magnetic needle" comes from the noun "needle", which is a thin, pointed instrument used for sewing or for other purposes, and the adjective "magnetic", which describes something that has the properties of a magnet.
The word "magnetic needle" was first used in English in the 16th century. It was originally used to describe the needle of a compass, but it soon came to be used in a more general sense to describe any small, magnetized needle that is free to pivot on a point.
Question
Where might you find a magnetic needle?
AQA Science Exam Question and Answer
Question:
Explain the significance of a magnetic needle in navigation and how it aligns with the Earth's magnetic field. Discuss how a magnetic needle is used to find directions.
Answer:
A magnetic needle plays a crucial role in navigation, helping travellers determine directions, especially when traditional landmarks are not visible. The principle behind its function lies in its alignment with Earth's magnetic field. The Earth acts as a giant magnet, with its magnetic north pole located near the geographic south pole and vice versa.
A magnetic needle, often mounted on a pivot, aligns itself with Earth's magnetic field lines. Its north end points towards the Earth's magnetic north pole and its south end towards the magnetic south pole. This alignment enables people to find the cardinal directions: north, south, east, and west.
Using a magnetic needle, a simple yet effective tool known as a magnetic compass is created. When the compass is held horizontally, the needle aligns with the magnetic field, indicating the direction of magnetic north. This information can then be used to determine other directions accurately.
However, it's important to note that the magnetic north pole is not exactly aligned with the geographic north pole. This difference is called magnetic declination and varies by location. To find true geographic north, navigators must adjust for this declination.