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प्रश्न
Have you seen someone blowing on their spectacles to wipe them clean? How does the air from the mouth help in cleaning the spectacles?
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उत्तर
The air blown from the mouth is hot and the glass of the spectacles is comparatively colder. The hot air we breathe out contains water vapours which turn into tiny droplets of water when it comes in contact with the colder glass. This makes the glass moist and hazy.
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संबंधित प्रश्न
Miya Balishtiye was confused when he saw the woodcutter blowing on his cold hands to make them warm and on the hot potatoes to cool them.
- Have you warmed your hands in winter by blowing on them when they are cold? How does it feel?
Balishtiye saw that the woodcutter was trying to cool the hot potatoes by blowing on them. What would have happened if he had eaten the potatoes without cooling them?
Picture 1 - Mini tried to cool her tea by blowing on it. Which do you think will be hotter – Mini’s tea or the air she blew from her mouth?
Picture 2 - Sonu was feeling very cold. He kept blowing onto his hands. Now think and write, which will be cooler – Sonu’s hands or his breath?
Put your finger under your nose. Can you feel any air when you breathe out from your nose?
Jump 30 times. Did you feel breathless?
Now again count how many times in one minute you breathed in and out.
Can you make a mirror hazy in the same way? Can you tell by touching the mirror what made it hazy? Is the air you blew from your mouth dry or wet?
Measure your chest
– Take a deep breath in
– Ask your friend to measure your chest with a thread. Measurement ____________
– Now breathe out. Again ask your friend to measure your chest. Measurement ____________
– Was there any difference in the two measurements of your chest?
You have all heard the ‘tick tick’ of the clock. Have you seen a doctor using a stethoscope to listen to our chest? What do you think she hears? Where is the sound coming from? Is there a clock inside your chest that keeps ticking away?
