Studied by 32 peoplePower equation without pd(letters)
I(2)R
Power equation(letters)
V x A
Energy transferred equation(letters)
W x s
power of an appliance is the energy it
transfers per second
Total energy transferred depends on
how long the appliance is on its power
Live wire
can give you an electric shock
Earth wire
green and yellow, for safety and protects the wiring
Neutral wire
blue, completes the circuit and balances it
Live wire
brown, provides the alternating current
mains supply is
ac
battery supply is
dc
In cool conditions
the thermistor resistance goes up
In hot conditions
the thermistor resistance drops
In darkness
LDR resistance in at its highest
In bright light
LDR resistance falls
LDR is a resistor that is
dependent on the intensity of light
a thermistor is a
temperature resistor
ohmic conductors have a
constant resistance
resistance unit
ohm
Charge flow equation(letters)
Q=It
voltmeter measures
potential difference in volts
ammeter measures
current in amps
Pd equation
a x q
Electric current is the flow of
electrical charge
Doing work
Energy transferred. Done when current flows or by a force moving an object
Kinetic energy equation
1/2 x mass x speed
Gravitational Potential energy equation
Mass x gravitational strength x height
Elastic Potential energy equation
1/2 x spring constant x extension
Specific heat capacity
The amount of energy needed to raise the temperature ok 1kg of a substance by 1 Celsius
Specific heat capacity equation
Change in thermal energy = mass x specific heat capacity x temperature change
Conservation of energy principle
Energy can be transferred usefully, stored or dissipated but can never be created or destroyed
Power equations(2)
Power = Energy transferred / time or Power = work done / time
Power
Rate of doing work
Conduction
Is the process where vibrating particles transfer energy to neighbouring particles
Convection
Where energetic particles particles move away from hotter to cooler regions
Efficiency equations(2)
Efficiency = useful output energy transfer / total input energy transfer or efficiency = useful power output / total power input
Non-renewable
Will run out
Non-renewable energy resources
Coal, gas, oil
Renewable
Will never run out
Renewable energy resources
Solar, wind, water waves, hydro-electricity, bio-fuels, tides, geothermal
Bio-fuels
Energy created from plant products or animal dung
Hydro-electric power
Requires the flooding of a valley by building a big dam
Wave power
Turbines in the water
Solar cells
Generate electric currents directly from sunlight
Geothermal power
Possible in volcanic area or where hot rocks lie quite near
Wind power
Putting wind turbines in windy areas like Scotland
Note
Flashcard