Energy Resources And Energy Transfer

Question 1

What is the principle of conservation of energy

Answer 1

Energy can be stored, transferred between stores, and dissipated, but it can never be created nor destroyed

Question 2

What are the 4 main ways energy is transfered

Answer 2

Mechanically (force acting on it)
Electrically (charge moving through a potential difference)
By radiation (hotter object to a colder object)
By heating (by light/sound waves)

Question 3

Describe the energy transfers involved as a ball rolls up a slope

Answer 3

Energy is transferred mechanically from the kinetic stores of the ball to its gravitational potential energy store
Some energy is transferred mechanically to the thermal energy store of the ball and the slope due to friction
Energy is wasted by heating to thermal energy stores of heating

Question 4

Describe the energy transfers as a bat hits a ball

Answer 4

Energy is wasted by sound or to the thermal energy stores of the bat
Energy is transferred mechanically from the kinetic energy store of the bat to the kinetic energy store of the ball

Question 5

Describe the energy transfers involved as an electric kettle boils water

Answer 5

Energy is transferred electrically from the thermal energy store of the element that is heating the kettle to the thermal energy store of the water

Question 6

Describe the energy transfers involved as a battery powers a toy car

Answer 6

Energy is transferred electrically from the chemical energy store of the battery to the kinetic energy store of the car and carried away by light from the headlights
Energy is Wasted by heating to thermal energy stores of the car and surroundings as well as energy carried away by sound

Question 7

Describe the energy transfers involved in a Bunsen burner and beaker

Answer 7

Energy is transferred by heating from the chemical energy store of the gas to the thermal energy stores of the beaker and water
Energy is wasted by heating to thermal energy stored of the stand and the surroundings as well as being carries away as light

Question 8

Explain how thermal radiation can occur

Answer 8

Objects emit and absorb IR
An object hotter than its surroundings emits more than it absorbs

Question 9

Explain how conduction can occur

Answer 9

Vibrating particles transfer energy from their kinetic energy store to the kinetic energy stores of neighbouring particles

Question 10

Describe an experiment to show conduction

Answer 10

Attach beads at intervals to one half of a long metal bar using wax
Use a Bunsen burner to heat the side of the bar with no beads attached
As time goes on, energy is transferred by through the metal by conduction, causing a rise in temperature
The wax holding the beads will begin to melt, and the beads will begin to fall, starting with the bead closest to the point of heating

Question 11

Explain how convection can happen

Answer 11

More energetic particles move from a hotter region to the cooler region

Question 12

Explain the immersion heater example of convection

Answer 12

Energy is transferred to the water from the heater coils
Hot water is less dense so begins to rise
Fast moving particles collide with slow moving particles and transfer energy
Water cools and becomes more dense and begins to sink again

Question 13

Describe an experiment to show convection happens using potassium permanganate crystals

Answer 13

Place some potassium permanganate crystals in a beaker of water and heat using a Bunsen burner
As the water temperature rises, the crystals begin to dissolve to form a bright purple solution
The purple solution begins to trace out the path of the convection currents in the beaker as it is carried through the water by convection

Question 14

Describe how you can reduce the rate of energy transfer

Answer 14

Stop the fluid from moving and prevent convection currents from forming
Using insulation (low thermal conductivity) such as clothes and foam cavity wall insulation works by trapping pockets of air
Air can’t move so energy conduction is very slow through the pockets of air
Some colours and surfaces will absorb and emit IR radiation better than others
E.g. a black surface is better than a white surface and a Matt surface is better than a shiny one
So using a shiny, white surface will reduce thermal radiation

Question 15

Describe how you can investigate the emission of thermal radiation

Answer 15

Place an empty Leslie cube on a heat proof mat
Fill it with boiled water and record the temperature of all four faces using a thermometer, they should all have the same temperature
Hold an IR detector a set distance away from one of the cubes faces and record the amount of IR radiation it detects
Repeat this for each of the surfaces of the cubes faces and repeat the experiment more than once
Be careful to avoid burns
You should find that more IR is detected on the black surface than the white surface, and more IR detected on the matt surfaces than the shiny surfaces

Question 16

What is work done

Answer 16

The amount of energy transferred

Question 17

What is power

Answer 17

The rate at which energy is transferred

Question 18

When an object is falling with no resistance, what two stores are equal

Answer 18

Energy lost from the gravitational potential energy store of the object and the energy gained in the kinetic energy store of the object

Question 19

What is a non-renewable energy resource and what is an example

Answer 19

A finite resource that will run out one day
E.g. coal, oil, nuclear fuels, natural gases

Question 20

Describe the energy transfers involved in a power station

Answer 20

Energy in the chemical energy store of the fossil fuel is transferred to thermal energy store of the water following combustion
The water boils to form steam which turns the turbine, transferring energy mechanically to the kinetic energy store of the turbine
The generator produces a current which transfers energy electrically away from the power station
Energy is lost by heating to the thermal energy stores of the surroundings

Question 21

What are the advantages of fossil fuels

Answer 21

Releases a large amount of energy relative to price
Doesn’t rely on weather

Question 22

What are the disadvantages of fossil fuels

Answer 22

Releases carbon dioxide into the atmosphere
Releases sulphur dioxide into the atmosphere
They are eventually going to run out

Question 23

What are the advantages and disadvantages of nuclear reactors

Answer 23

Advantages = Doesn’t produce any greenhouse gases and there is still lots of uranium left in the ground to be used for the reactions

Disadvantages = Expensive to build and maintain, risk of radioactive material leakage, radioactive waste, when they get too old and inefficient they are decommissioned, which is very expensive

Question 24

What are the advantages and disadvantages of wind turbines

Answer 24

Advantages = They are cheap to maintain, reliable, renewable, and don’t produce greenhouse gases

Disadvantages = They spoil the view, they are very noisy, they are to reliant on the weather, expensive to setup a wind farm

Question 25

How does geothermal power work

Answer 25

Water is pumped down to the hot rocks and forced back up due to pressure to turn which drives a generator

Question 26

What are the advantages and disadvantages of geothermal power

Answer 26

Advantages = They can directly heat buildings, they are free, renewable, and have no environmental problems Disadvantages = They cost a lot to drill down into the Earth several km, they are very expensive when compared to the energy they produce

Question 27

What are the advantages and disadvantages of solar cells

Answer 27

Advantages = They are a renewable source (the Sun), very affordable following initial investment, they cause no pollution Disadvantages = They generate energy on a relatively small scale, too expensive to connect to national grid, can only generate useful energy with sunlight (not useful in the night and during the winter in some places)

Question 28

Describe how solar heating can be used to heat water

Answer 28

Black water pipes inside a glass box which absorb energy from the sun which heats up the water, they are renewable and free to use following initial installation

Question 29

Describe how solar heating systems can be used for cooking

Answer 29

Curved mirrors that can focus the Sun’s light e.g. a solar oven It is renewable but is slow, bulky, and unreliable as it needs strong sunlight to work

Question 30

What are the advantages and disadvantages of wave power

Answer 30

Advantages = No pollution, renewable, no fuel costs, minimal maintenance costs Disadvantages = spoiling the view, hazard to boats, unreliable when waves die out following dropping of wind

Question 31

What are the advantages and disadvantages of tidal barrages

Answer 31

Advantages = No pollution, it is renewable, fairly reliable, no fuel costs, and minimal maintenance costs Disadvantages = Prevents free access by boats, spoils the view, altering the habitats of wildlife, low tides will reduce energy production

Question 32

What are the advantages and disadvantages of hydroelectricity

Answer 32

Advantages = It is renewable, there is no pollution, national grid can supply it with sufficient energy, reliable, no fuel costs, and minimal maintenance costs Disadvantages = Possible loss of habitat for some species, unattractive, affected by drought, risk of flooding of valley (methane and carbon dioxide can be released by rotting vegetables)

Question 33

What is pumped storage

Answer 33

Extra night-time electricity is used to pump water up to a higher reservoir This can be released during periods of peak demand

Question 34

How do wind turbines work

Answer 34

Energy from the kinetic energy store of air is used to generate electricity as it turns the bladed which turn the generator inside of the turbine

Question 35

How does geothermal power work

Answer 35

Decaying of radioactive elements underground, energy is transferred from the thermal energy stores to the kinetic energy stores and is used to generate electricity

Question 36

How does wave power work

Answer 36

Small wave converters are located around the coast, they provide an up and down motion which can be used to drive a generator Energy is transferred from the kinetic energy stores of the waves to the kinetic energy store of the turbine

Question 37

How do tidal barrages work

Answer 37

Large dams built across river estuaries with turbines in them, as the tide comes in, the estuary is filled with water to a height of several meters Energy is transferred from the kinetic energy stores of the water to the kinetic energy stores of the turbine

Question 38

How does hydroelectricity work

Answer 38

Rainwater is caught and allowed out through turbines Energy is transferred from the gravitational potential energy stores of the water to the kinetic energy stores of the water as it falls

Question 39

How do nuclear reactors work

Answer 39

Nuclear fission of uranium is used to produce heat to make steam to drive the turbines Energy is transferred from the nuclear energy stored to the thermal energy stores, then transferred mechanically to the kinetic energy stores, and finally transferred electrically through the national grid