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Waves and heat transfer revision: red shift, U-values
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- 1U-VALUESShows how good a material/building component is as an insulator. The lower it is, the less energy the material transfers.
- 2HEAT TRANSFER FROM BUILDINGS/OBJECTSReducing heating bills-insulation, install alternative sources of energy, heats the building through solar panels for hot water for washing. Payback time-time it takes to pay something over a period of time. shorter it is, more cost effective. e.g. costs £60 to insulate water tank & saves £15. Payback time=4 years.
- 3PAYING FOR ELECTRICITYBills-amount of energy used. 'J'-small amount of energy. kWh-amount of energy transferred by a kW device in 1 hour. Energy transferred=power x time. Total cost=no. of kWh x cost per kWh.
- 4EQUATIONSPower/electrical power-watts (W)
Resistance-ohms
Acceleration-m/s 2
Efficiency-%
Yield-%
Work done-joules (J) - 5HEAT TRANSFER FROM BUILDINGS/OBJECTSEnergy from sun can heat houses directly. U-value is part of the regulations for building a house for roofs, walls & floors. low energy house-thick concrete walls/floor, earth bank on sides, glass room, triple glazed windows, foam insulation, air in houses.
- 6SPECIFIC HEAT CAPACITYEnergy needed to raise 1 kg of water by 1 degrees C. The amount of energy stored in an object depends on its mass.heat transferred=mass x SHC x temp. change. e.g. how much does a kettle transfer when it heats 1 kg of water from 100 degrees C. The SHC of water is 4200 degrees C.
- 7RED & BLUE SHIFTRed shift is one example of the Doppler effect. When an object moves away from an observer, its light is affected by the Doppler effect. If the source is further away, the wavelength is bigger, if the source is approaching, the wavelength decreases-blue shift.
- 8REFLECTIONWhen waves bounce off a surface like a mirror. First perpendicular line (normal) and the angle of incidence (i)=the angle of reflection (r).
- 9MIRROR IMAGEThe image formed by a plane mirror is the same distance behind as the object is in front of it. The image is called the virtual image.
- 10WAVESTransverse-the oscillations are perpendicular to the direction of energy transfer. Longitudinal-the oscillations are parallel to the direction of energy transfer.
- 11SOUNDLongitudinal waves cause vibrations in the medium. Pitch is determined by its frequency and loudness by its amplitude. Echoes are reflections of sound.
- 12WAVE MOVEMENTRarefaction-spread out. Refraction-change direction.
- 13DIFFRACTION AND REFRACTIONThe spreading out of waves and pass through a narrow gap, effect is most noticeable when gap is same size as the wavelength of the wave.
Change in direction of a wave as it goes through an interface into a different material, different speed. Hits a glass block, slows down. - 14DOPPLER EFFECTWhen a wave source is moving relative to an observer, there will be a change in observed wavelength and frequency. Wavelength-sound/microwaves. Further the source-wavelength increases, frequency decreases. Closer source-wavelength decreases, frequency increase.
- 15CMBRCosmic microwave background radiation. Comes from radiation soon after the beginning of the universe. A form of electromagnetic radiation filling the universe. Big Bang-only theory that explains CMBR.
- 16BIG BANGStarted in one place. Big explosion. Expanding.
- 17MICROWAVESMicrowaves heat food by causing the water particles in the food to vibrate causing heat energy.
- 18HOW RED SHIFT PROVIDES EVIDENCE FOR THE BIG BANG1)Wavelength has increased so the galaxy must be further away from us which proves the universe is expanding.
2)Moving toward the red end of the spectrum. Further toward the red end, further away it is, proves the universe is expanding. - 19ELECTROMAGNETIC SPECTRUMReading magazines is very unpleasant & xtremely gay. (radio, micro, infrared, visible light, ultra violet, x-ray, gamma).
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- Fichas sobre Sin título, creado por Lucy Gutowski el 09/10/2014.
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