Unit 1 Flashcards
Describe Red Shift
- galaxies moving away
- wavelength increases
- frequency decreases
- more distant, bigger shift
What does step up transformer do?
- increase voltage
- decrease current
- decrease energy loss
- increase efficiency
How does standby damage environment?
- electricity needs to be generated
- power stations needed
- fossil fuels burnt -> greenhouse gases -> global warming
Pros of nuclear power (8)
- no greenhouse gases
- high energy density in fuel
- longer operating life
- reliable
- small volume of waste
- buy less fuel from other countries
- concentrated source of energy
- fossil fuels last longer (conserves fossil fuels)
Pros of wind energy (6)
- no greenhouse gases
- small plot of land, still used for farming
- low running costs
- renewable
- energy source (wind) free
- conserves fossil fuels
Cons of wind energy (8)
- kills birds
- noise
- eyesore
- unreliable cuz weather dependent
- dilute energy source
- large initial cost
- times when not enough electricity generated
- co2 used in manufacture
What is a digital signal
signal that has two states
What is an analogue signal
signal caries continuously
What is the big bang?
- universe expanding
- after explosion at one pint
Pro of sending info as digital not analogue
- less interference
- signal restored
- easily accessible by computer
Con of fossil fuels
- release co2
- leads to global warming
Properties of EM waves
- travel through vacuum
- at same speeds
- can be reflected
- can be refracted
What happens to wasted energy?
- transferred to surroundings as heat
- not usually transformed
- spreads out and diff to use usefully for further energy transformations
What is specific heat capacity?
amount of energy required to change the temperature of one kilogram of the substance by 1 degree Celsius
Why devices on standby damage environment/ why reducing energy reduces co2 emitted in a (converse)
- ff burnt - global conserves, less greenhouse
- uses electricity which needs to be generated
- power stations needed
What is energy efficient?
- smaller proportion of energy supplied is wasted
- most energy usefully transformed
How does the design of a black stove/radiator improve rate of energy transfer?
- black is good emitter of infrared
- give max energy transfer
- matt better emitters
- large sa
Why temp fall fastest just after switches off/water cooled faster first 5 mins (converse for what happens to energy transfer with heater when switched off) (2)
- bigger energy diff between water and surrounding air
- so transfer of energy is faster
Why fins affect rate of energy transfer (converse small ears help in cold)(2)
- Fins increase SA/decrease
- so rate of energy transfer/evaporation increases/decreases
How is heat transferred by convection from bottom to top of oven?
- particles gain energy
- move faster
- move apart
- air expands
- less dense
- hot air rises
Why (this) light and shiny?
- less heat loss
- poor emitters of radiation
Why is the fridge light and shiny?
- poor absorber of heat
- good reflector of heat
- reduces heat transfer into fridge
Why does the energy supplied equal the energy transferred?
energy cannot be destroyed
Does the fridge or the freezer have the greatest rate of energy transfer?
- freezer
- greater temp diff between freezer and room