What is the purpose of moving a magnet along a needle in the compass-making procedure?

• A. to give the needle an electric charge
• B. to make the needle sharper
• C. to magnetize the needle
• D. to flatten the side of the needle

Answer: (C)

The purpose of moving a magnet along a needle during the compass-making procedure is to magnetize the needle. When a magnet is stroked along a ferromagnetic material, such as iron or steel used in the needle, it aligns the internal magnetic domains of the material in the direction of the magnet's magnetic field. This alignment creates a permanent magnet within the needle, allowing it to respond to magnetic fields, such as the Earth's magnetic field, and thus function effectively as a compass. The increased alignment of these domains imparts a North-South orientation to the needle when it is freely suspended, enabling it to point toward the magnetic poles.

Other potential options, while they might seem plausible at a glance, do not accurately reflect the actual mechanism at play in this procedure. For instance, charging the needle electrically would not help it function as a compass, and sharpening the needle would not contribute to its magnetic properties either. Additionally, flattening the side of the needle does not play any role in enhancing its magnetization or overall performance as a compass. Hence, the primary goal of using a magnet in this context is to magnetize the needle effectively.