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Heat Transfer P1
Question | Answer |
---|---|
Where on an object i heat radiation emitted from? | The surface |
Why does surface area increase radiation? | Because more infrared waves can be emitted from the surface and so heat transfer is quicker |
Give two uses of increasing surface area to increase radiation. | • Radiators have large surface areas to maximise heat transfer • Car have large fins so heat radiates and engine cools quicker |
What happens if two objects, one with a large volume and the other with a small volume, at the same temperature radiate? | The object with the smaller volume will radiate heat and cool quicker because a higher proportion of its surface is in contact with its surroundings |
How can the type of material affect rate of heat transfer? | An object in contact with a good conductor will radiate more heat than an object in contact with a good insulator |
In a vacuum flask, which features stop: a) Conduction (3) b) Convection (1) c) Radiation (1)? | a) Double walled with vacuum, insulating foam and plastic stopper filled with cork b) Double walled with vacuum c) Silver wall |
Why do arctic foxes have small ears? | To minimise heat loss by radiation due to surface area |
Why do desert foxes have huge ears? | To allow them to lose heat due to large surface area to keep cool |