Flashcards
PHYSICS P1 1
Flashcards do conjunto (27)
- 1Which objects absorb and emit infrared radiation?All objects emit and absorb infrared radiation
- 2what makes an object radiate more infrared radiation?How hot it is, the hotter the object the more infrared radiation it radiates
- 3What type of surface is perfect for emitting and absorbing infrared radiation?Dark, matt surfaces are good at absorbing and emitting infrared radiation.
- 4what makes a bad surface for emitting and absorbing infrared radiation?Light, shiny surfaces are bad at emitting and absorbing infrared radiation.
- 5What sort of surface would be good at reflecting infrared radiation?Light, shiny surfaces
- 6What does a fluid do when heated?Expands, becomes less dense, rises and causes circulation (convection)
- 7Infrared radiation is transfer of energy by what type of wave?Electromagnetic waves
- 8What are all materials made out of?particles
- 9What are the best conductors of energy?Metals
- 10What materials are the best insulators?Wool and fibreglass
- 11How does conduction take place?free electrons transfer energy inside metals
- 12Why are non metals not good at conducting?They don't have free electrons
- 13What is convection?The circulation of a fluid (liquid or gas) caused by heating it
- 14What is evaporation?When a liquid turns into a gas
- 15What is condensation?When a gas tuns into a liquid
- 16How does evaporation cause cooling?The faster moving-molecules escape from the liquid
- 17How can evaporation be increased?-Increase the surface area of the liquid
-Increase the temperature of the liquid
-Create a draught of air across the liquid's surface - 18How can condensation on a surface be increased?-Increase the area of the surface
-Reduce the temperature of the surface - 19What does the rate of energy transfer to or from an object depend on?-The size, shape and type of material of the object
-The materials the object is in contact with
-The temperature difference between the object and its surroundings - 20How will the mass of an object change how quickly the temperature changes when heated?The greater the mass, the slower the temperature increases.
- 21What does the rate of a substance's temperature change depend on when it is heated?-The energy supplied to it
-Its mass
-Its specific heat capacity - 22What is specific heat capacity?The energy required to raise 1kg of a substance by 1 degree Celsius
- 23How do you work out specific heat capacity?c= E
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m x (theta)
E=Energy transferred (J)
m=Mass (kg)
c= Specific head capacity (j/kg oC)
theta=temperature change (oC) - 24How can energy transfer be reduced in our homes?-Loft insulation
-Cavity wall insulation
-Double Glazing
-Draught excluders
-Aluminium foil behind radiators - 25What does a U-Value tell us?How much energy per second travels through a material.
- 26What does a low U-Value mean?The material is a good insulator
- 27What does a high U-Value mean?The material is bad at insulating