Question

The chimney of an oil lamp cracks when touched with rhe brade of cold knife?why
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Answer 1

The extreme difference between the hot chimney and the cold knife makes the chimney expand and contract so quickly it cracks.

Step-by-step explanation:

Hope this helped!

Answer 2

When a blade of cold knife is touched to hot glass chimney there is a sudden drop of temperature on the spot where the blade touches. As a result it cracks.

Step-by-step explanation:

When a blade of cold knife is touched to hot glass chimney there is a sudden drop of temperature on the spot where the blade touches. This decrease in temperature makes the glass to contract. The stress developed on the site of contraction is responsible for the cracking of the glass chimney.