G. 10 Science questions needed answered please?

Question

Heres the remaining questions of my homework that I'm not exactly sure about? Any help is appreciated!

1) Why should you never leave a thermometer resting on the bottom of a beaker when heating a liquid?

2)Why does a typical desk lamp have small holes on the top of the metal lampshade?

I was thinking for that first question is because the liquid is covering the entire thermometer and affects how it takes the temperature. Not exactly sure about that or the second one.

Thanks!

Answer 1

//////////////////////// temperature questions

The point of contact between the thermometer body and the glass beaker might transfer heat faster than the liquid does. This would give an inaccurate temperature reading.

Desk lamps have small holes in the back because the air around the bulb heats up and rises because it is less dense. This is how a hot air baloon operates. If the bottom of the shade is parallel to the ground, a bubble of hot air can build up inside the shade and this might cause the bulb to overheat. The holes allow the hot air to escape and this draws cooler air into the shade to replace the warm air exiting the holes. This keeps the bulb and the shade cool.

Answer 2

the bottom may get hotter than the liquid and overheat the thermometer, and cause false readings.

ventilation, to dissipate the heat from the bulb.

Answer 3

1. The thermometer would take the temperature of the glass also, so you must keep it from touching any other surfaces than the water.

2. The metal of the lamp would over heat, possibly melting the metal.