Chapter 2 - Energy Transfer by Heating Flashcards
Why do steel pans have handles of plastic/wood instead of metal?
- Plastic and wood are insulators, which would keep the handle cool and prevent the user from burning their hand.
Give 2 examples of good insulating material that could be used for roof insulation.
- Wool
- Fibreglass
Give 3 factors that affect the energy transfer per second through an insulating material.
- Temp difference across the material.
- Thickness.
- Thermal conductivity.
Give 2 ideal characteristics of an insulating material to insulate a room.
- Low thermal conductivity.
- Very thick materal.
Which type of objects emit and absorb infrared radiation?
- All objects
The hotter an object is………
…….the more infrared radiation is emitted in a given time.
What is blackbody radiation?
- Radiation emitted by a body that absorbs all radiation on it.
When the temperature of an object increases…….
……..it absorbs more radiation than it emits.
Give 2 factors which affect the Earth’s temperature.
- Absorption of infrared radiation from the sun.
- Emission of radiation from the Earth’s surface/atmosphere.
How do greenhouse gases make the Earth warmer?
- Greenhouse gases such as Co2 absorb longer wavelength infrared radiation and prevent it escaping into space, trapping the heat in.
Define specific heat capacity.
- The energy needed to raise the temperature of 1kg of the substance by 1 degrees celcius.
How do you calculate the energy transferred?
Energy transferred = mass(m) x specific heat capacity (c) x temperature change
The greater the mass of the object………
……..the slower its temperature increases when heated.
How do you find the specific heat capacity?
Mass x Temp Change
Give 5 materials that can be used inside a house to reduce the rate of energy transfer.
- Loft insulation
- Cavity wall insulation
- Double - glazed windows
- Aluminium foil behind radiators
- Walls of thicker bricks
