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Question
If a watch-glass containing a small quantity of water is placed on two dissimilar magnetic poles, then water ______.
Options
shows a depression in the middle.
shows an elevation in the middle.
surface remains horizontal.
evaporates immediately.
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Solution
If a watch-glass containing a small quantity of water is placed on two dissimilar magnetic poles, then water shows a depression in the middle.
Explanation:
When a watch glass containing water is placed over two dissimilar magnetic poles (such as north and south poles placed close to each other), a non-uniform magnetic field is created.
Water is a diamagnetic substance, meaning it is weakly repelled by a magnetic field. In a non-uniform magnetic field:
- The water molecules are repelled away from the region of stronger magnetic field.
- Since the magnetic field is strongest near the poles and weaker at the centre between them, the water is pushed outward.
- This causes the water surface to dip in the centre, forming a depression.
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