Thermos flask

A thermos flask maintains the temperature of its contents by using a vacuum between its inner and outer walls, which acts as a thermal insulator. The vacuum prevents heat transfer, keeping hot liquids hot and cold liquids cold. The cap, made of insulating materials, further aids in maintaining the temperature. However, over time, some heat transfer occurs, altering the contents' temperature. The thermos flask reduces heat flow but cannot maintain the same temperature indefinitely.

What is the primary function of the vacuum in a thermos flask?

• To act as a barrier to heat transfer

• To provide structural support

• To allow heat to flow freely

• To store additional liquids

Why is the cap of a thermos flask made from materials like cork or plastic?

• To reduce the weight of the flask

• To enhance the aesthetic appeal

• To prevent heat transfer and maintain temperature

• To make the flask more durable

How does a thermos flask keep iced water cold?

• By releasing cold air

• By absorbing the cold

• By preventing heat from flowing in

• By allowing heat to flow in

What eventually happens to the contents of a thermos flask over time?

• They remain at the same temperature indefinitely

• They become hotter

• Their temperature changes due to heat transfer

• They become colder

What is the main role of a thermos flask?

• To reduce the flow of heat energy

• To completely stop heat flow

• To increase the temperature of its contents

• To cool down its contents