Infrared Radiation
- Created by: Georgia
- Created on: 01-12-17 16:57
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- Energy Transfer by heating
- Energy Transfer by Heating
- Thermal conductor = material that allows thermal energy to pass through
- Thermal insulator = material that doesn't allow thermal energy to pass through
- Rate of thermal energy transfer depends on:
- The temperature difference
- The thickness of the material
- The thermal conductivity of the material
- To reduce the rate:
- have as low a thermal conductivity of the material as possible
- The material should be as thick as possible
- Infrared radiation
- Part of the electromagnetic spectrum
- Makes us feel hot
- All objects give this off
- An object at a constant temperature emits the same amount as it absorbs
- An object that is getting hotter emits more radiation than it absorbs
- An object that is getting colder absorbs more than it emits
- An object with a light/shiny surface will absorb and emit less radiation than one with a dark/matt one
- Greenhouse Effect
- Earth receives infrared radiation from the sun
- Radiation from the sun is absorbed by the Earth's ground or atmosphere
- Some of the radiation is reflected by the ground but gets trapped by the gases in the air
- This is because the radiation is reflected at a shorter wavelength
- This causes the atmosphere to gradually heat up
- This is the greenhouse effect
- Specific Heat Capacity
- The amount energy needed to heat 1 kg of a substance 1C
- The higher it is, the more energy needed
- A greater mass requires more energy
- Calculating energy required to change the temp of a substance
- Energy = mass x s.h.c x temperature change
- mass measure in kg
- Energy = mass x s.h.c x temperature change
- Heating and insulating buildings
- People want to reduce the amount of heat lost from their houses
- Fiberglass roof insulation
- Cavity wall insulation
- Aluminium foil behind radiators
- Reflects infrared radiation back into the room
- Double glazing around the windows
- Thick bricks with low thermal conductivity
- Solar Panels
- Absorb infrared radiation from the sun
- Cells generate electricity directly
- HEating panels heat water directly
- Perfect Black bodies
- Absorbs all the radiation that hist them
- Best possible emitter of radiation
- Radiation from them is clled black body radiation
- Energy Transfer by Heating
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