WHY do ballpoint pens have a small hole halfway down them?
If the inside of the pen were completely airtight the pressure inside would fall as the ink in the cartridge was used up.
This change in pressure would affect the flow of ink from pen to paper.
The hole allows the air pressure to equalise and prevents problems with the ink flow.
Why Can't Elephants Jump?, Profile Books
Power of the ballpoint pen
WHY do ballpoint pens have a small hole halfway down them?
If the inside of the pen were completely airtight the pressure inside would fall as the ink in the cartridge was used up.
This change in pressure would affect the flow of ink from pen to paper.
The hole allows the air pressure to equalise and prevents problems with the ink flow.
Why Can't Elephants Jump?, Profile Books
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