Energy Flashcards
Explain how electricity can be generated from coal.
- Coal is burned in a power station.
- The heat boils water which turns into steam.
- The steam turns the turbines which turn the motor.
4. Electricity is generated.
Explain what the word ‘equilibrium’ means and give an example.
When things reach an equal.
E.g. hot tea reaching room temperature after being left on a table.
Explain how heat is transferred by Conduction.
Heat is transferred through solids by conduction.
Particles pass on energy to neighbouring particles which vibrate more
Explain how heat is transferred by Convection.
The particles in liquids and gases can move from place to place.
Convection happens when particles with a lot of thermal energy in a liquid or gas move, and take the place of particles with less thermal energy.
Thermal energy is transferred from hot places to cold places by convection.
The potential difference across a bulb is 3V and the current in 0.2A.
a) Calculate the power
Power(P)= Voltage (V) x Current (I)
b) Calculate the energy transferred (in joules) by the bulb in 10 seconds.
Energy (E)=Power (P) x time (t)
a) P= V x I
3 V x 0.2 A = 0.6W
b) E= P x t
0. 6w x 10s = 6j
- Explain how heat is transferred by radiation.
- Why would a marathon runner use a foil blanket after the race?
- Radiation does not need particles. It is also known as infrared radiation and the more red something is, the hotter it is.
- The foil blanket reflects the radiated heat back onto their body.
- You want to reduce your energy bills.
Calculate the power of a lightbulb that transfers 6000J every minute.
P = E / t
- Change 56MW into W (1 MW= 1 million W)
Power = Energy transferred divided by time
P=E/t
6000J / 60s = 100w
- Change 56MW → 56000000W
a) A car engine that uses a force of 500N to move a car 200m
Work done (Wd) = Force (f) x distance (d)
b) A shopkeeper who uses a force of 50N to lift a box 1.5m
a) Wd = f x d
500N x 200m = 100000j
b) Wd = f x d
50N x 1.5m = 75j
Describe where and how energy is stored in a torch and what happens when it is switched on?
Energy is stored in the battery as chemical energy. This is transferred into electrical energy and then to heat and light when the torch is turned on,
List some renewable and non-renewable energy source below. Then give advantages and disadvantages for both.
Renewable- solar, wind, wave, geothermal, tidal, hydroelectric, biomass
Non-renewable: fossil fuels- coal, oil, gas, wood.
What is the conservation of energy?
Energy cannot be made nor destroyed
Draw the formula triangle for:
a) power
b) Work done
Plot a graph of power against wind speed and describe the relationship between the two.
Wind speed (km/h) Power (W)
1 10
2 75
4 245
7 420
9 670
10 980
15 1000
20 1000
23 1000
As the wind speed increases, the power also increases up until 15km/h where the maximum power of 1000w is produced.
