Tag: thermo flask

Questions Related to thermo flask

Thermos flask prevents loss or gain of heat by

thermo flask thermos flask heat energy transfers transfer of heat physics

  1. conduction only

  2. convections only

  3. radiation only

  4. all of the above

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Correct Option: C

Thermos flask, when closed, is an approximate

thermo flask thermos flask heat energy transfers transfer of heat physics

  1. open system.

  2. closed system.

  3. isolated system.

  4. None of these

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Correct Option: C
Explanation:

An open system is a one which can exchange matter as well as energy with the surroundings. Eg: a beaker of water. A closed system is a one which can exchange only energy with the surroundings. Eg: a liquid in a closed bottle. An isolated system is a one which cannot exchange anything with the surroundings. Eg: Thermos Flask .

Liquid nitrogen is stored at $77K$ in a vacuum flask. The surrounding atmospheric temperature in the lab is $33K$.

thermo flask thermos flask heat energy transfers transfer of heat physics

  1. After a few days, the temperature of liquid nitrogen will increase.

  2. After a few days, the temperature of the lab will decrease.

  3. After a few days, the temperature of liquid nitrogen will decrease

  4. After a few days, the temperature of liquid nitrogen will remain unchanged.

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Correct Option: D
Explanation:
Liquid nitrogen is stored at $77K$ in vacuum flask. The surrounding atmosphere temperature of the lab is $33K$.
After a few days, the temperature of liquid nitrogen will remain unchanged. Because, vacuum flask is designed to prevent heat loss by conduction, convection and radiation. So, the temperature remains unchanged.

Which of the following is an insulating component in thermos flask?

thermo flask thermos flask heat energy transfers transfer of heat physics

  1. plastic foam

  2. air

  3. vacuum

  4. All of the above

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Correct Option: D
Explanation:
Insulating component in thermos flask are plastic foam, air, vacuum.
As plastic foam is insulator, so to prevent heat to radiate plastic foam is used just after the inner layer, plastic foam is being polished to reflect the inner heat inside, as air is bad conductor of heat it does not conduct heat just outside the outer layer. Vacuum is poor conductor of heat. It is situated between two layers, which prevents heat conduction through convection.

The purpose of using vacuum flask is to store

thermo flask thermos flask heat energy transfers transfer of heat physics

  1. hot drinks.

  2. cold drinks.

  3. hot as well as cold drinks.

  4. None of these

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Correct Option: C
Explanation:
The purpose of using the vacuum flask is to store hot as well as cold drinks.
The basic concept behind using the vacuum flask is to keep the temperature of liquid constant which is being kept in the flask, no heat transfer would take place via conduction, convection or radiation.

A themoflask prevent heat loss from-

thermo flask thermos flask heat energy transfers transfer of heat physics

  1. Conduction

  2. Convection

  3. radiation

  4. all of these

Show answer
Correct Option: D
Explanation:
A thermoflask prevent heat loss from conduction, convection and radiation.
As it has insulator between two layers, it prevents the direct contact with surrounding and also stops the molecular motion for heat transfer. As it is a closed system surrounded by the layer of insulator, radiation can't even take place.