Core Science; Physics

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  • Created by: Moonisah
  • Created on: 09-09-12 17:23
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Moonisah Mirza
Physics core science
1. What is thermal radiation? Thermal radiation is energy transfer by electromagnetic
waves.
2. What emits thermal radiation? All objects emit thermal radiation, the hotter the
object the more thermal radiation it emits.
3. What objects are good emitters and absorbers of thermal radiation? Good emitters
and absorbers of thermal radiation are surfaces which are dark and matt. Matt
surfaces absorb radiation better as it has more cavities, they trap and absorb
radiation.
4. What objects are poor emitters and absorbers of thermal radiation? Poor emitters
and absorbers of thermal radiation are surfaces which are light and shiny. Shiny
surfaces reflect the absorption.
5. What is conduction? Conduction is the transfer of energy in particles.
6. What is convection? Convection currents transfer thermal energy from hotter parts
to cooler parts. It only takes place in liquids and gases (fluids)
7. What affects the rate at which heat is transferred? The shape and dimensions of a
body affect the rate at which heat is transferred. The bigger the temperature
differences between a body and its surroundings the faster the rate at which heat is
transferred.
8. List the different types of energy transfers e.g. electrical energy, sound energy etc
chemical energy, gravitational potential energy, kinetic energy, elastic energy, thermal
energy.
9. How do you calculate the efficiency of a device? Efficiency = useful energy
transferred by a device / total energy supplied to the device x 100.
10. How is heat lost in the house? Ceilings, walls, doors, windows.
11. How can we insulate a house to prevent heat loss and save money? One could have
loft insulation, as it involves fibreglass which reduces heat loss. Aluminium between
radiators reflects heat energy away from the wall. Cavity wall insulation reduces the
heat lost through the walls. Double glazed windows have two glass panes with dry air
or a vacuum; this also cuts down heat conduction.
12. Can energy be created or destroyed? No
13. What happens when energy is transferred? When energy is transferred only one part
of it is usually transferred.
14. What happens to wasted energy? Wasted energy is eventually transferred to the
surroundings, the surrounding become hotter, energy becomes more spread out and
it becomes increasingly more difficult to use for further energy transformations.
15. How can you tell if a device is efficient?
16. How do you calculate energy transferred by a device? Energy transferred = power x
time (hours)

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Moonisah Mirza
17. How do you calculate the cost of electricity? Total cost = number of KW hours x
cost per KW hour.
18. What do you measure power of a device in? Watts or kilowatts.
19. How do we transfer electricity around the country? Through the national grid, the
national grid is a network of pylons and cables that covers the whole of Britain. The
electricity is made in power stations it is transmitted at high voltages across the
country.
20.…read more

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34. Do they all have the same wavelength? No, the energy they transfer depends on the
wavelength of the waves; this is why waves of different wavelengths have different
effects.
35. What are the uses of different EM radiation? Gamma rays- treatment of cancer
tumours, sterilisation of medical instruments. X-rays- examination of broken bones
and teeth, detecting diseased areas in the body.…read more

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45. What is an isotope? An isotope is an atom with a different number of neutrons and
but the same number of protons.
46. What is a half-life? A half life is the time it takes for half the nuclei in a sample to
decay.
47. What is the big bang? According to the big bang theory the whole universe was
compressed to a very tiny point, then it exploded and started to expand and the
expansion is still going on.
48.…read more

Comments

Anisa -Team GR

This is only questions.

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