Why is the glass around the thermometer so so thin?

Question

And why is the glass around the thermometer is like a magnifying glass?

This is gr.7 science.

please n thank you :)

Answer 1

The glass is like a magnifying glass because it is curved and light is bent (refracted) as it passes through. Lenses (magnifying glasses, reading glasses and even the lenses in your eyes) work as they do because of this same principal.

The glass is thin because  heat pass through glass quite slowly (Glass is a good insulator of heat.). If the glass was  thicker it would take quite awhile for a change of temperature to register on the thermometer.

Answer 2

The glass is shaped to magnify the width of the very narrow mercury (or dyed red alcohol) collumn so it is easier to see. As for the thinness of the bulb it is probably as the other answerer said, to maximize the rate of heat transfer and thus, measure the temperature more quickly/accurately.