Suspend the bar magnet freely using a string. The magnet will align itself with the Earth’s magnetic field. The end pointing towards the Earth’s geographic north is the magnet’s north pole, as opposites attract.
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To find the poles, bring the marked magnet close to the unmarked one. The north pole of the marked magnet will attract the south pole and repel the north pole of the unmarked magnet, revealing its poles.
Reshma can identify the magnets by bringing each bar close to the other two. If a bar repels one and attracts the other, it is a magnet. The iron bar will only be attracted.
Magnets in electric motors create a magnetic field that interacts with the current-carrying coil, producing rotational motion. This interaction between the magnetic field and electric current is fundamental to the motor’s operation.
The Earth’s magnetic field is a natural magnetic field generated by the movement of molten iron in the Earth’s outer core. It protects us from solar radiation and aids in navigation using compasses.
Temperature affects magnetism by altering the alignment of magnetic domains. At high temperatures, thermal energy disrupts this alignment, reducing a magnet’s strength. Extremely high temperatures can even demagnetize a material.
In a compass, a magnetized needle aligns itself with the Earth’s magnetic field, pointing toward the magnetic north. This allows users to determine direction relative to the Earth’s magnetic poles.
The strength of an electromagnet can be increased by increasing the electric current, adding more turns to the wire coil, or using a core with better magnetic properties, like soft iron.
Temporary magnets lose their magnetism quickly once the external magnetic field is removed, like soft iron. Permanent magnets, like bar magnets, retain their magnetism over time without needing an external field.
The law of magnetic poles states that like poles repel and unlike poles attract. This means that a north pole will attract a south pole but repel another north pole, and vice versa.