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Energy resources and energy transfers Flashcards

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1
Q

What are the 8 energy stores? (8KG CEMENT)

A

Kinetic

Gravitational

Chemical

Elastic

Magnetic

Electrostatic

Nuclear

Thermal

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2
Q

Energy transfer: Mechanical

A

When a force acts on a body

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3
Q

Energy transfer: Electrical

A

Electricity transferring energy from a power source to a component within a circuit

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4
Q

Energy transfer: Heating

A

Conduction, convection & radiation

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5
Q

Energy transfer: Radiation

A

Light & sound carry energy from one point to another

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6
Q

The principle of conservation of energy

A

Energy cannot be created or destroyed, only change form

Energy in = Energy Out

Energy in = (Useful out) + (Waste out)

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7
Q

Equation for efficiency:

A

Efficiency = Useful energy output / Total energy output x 100%

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8
Q

What is the input, waste & output energy of a car engine

A

Input: Chemical

Useful: Kinetic

Waste: Thermal

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9
Q

Sankey diagrams

A

A = input energy
- Width = energy (in joules)
- A is always left

B = useful output
- Width = energy (in joules)
- B goes to the right

C = Waste output
- Width = energy (In joules)
- C goes down

Energy in = Energy out -> A = B + C

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10
Q

The transfer of thermal energy

A

From a hotter area to a colder one

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11
Q

Conduction

A

Conduction occurs (mainly) in solids

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12
Q

Convection

A

Convection occurs in fluids (liquid & gas)

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13
Q

Radiation

A

(Infrared) radiation & electromagnetic wave that can travel through solids, liquids, gasses & vacuums

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14
Q

What happens to the particles in conduction?

A
  • Occurs mainly in solids
  • When an object is heated, particles begin to vibrate
  • When particles vibrate, they collide with other particles passing on energy
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15
Q

Why are metals good conductors?

A

They contain delocalised electrons which can collide with other atoms easily

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16
Q

Explain convection

A
  • Convection occurs in fluids (liquids & gases)
  • Fluid is heated, molecules are pushed apart (thermal expansion)
  • Hot fluid becomes less dense
  • Less dense fluid rises, cooled fluid sinks to replace it
  • Hot fluid cools, contracts & sinks
  • This phenomenon is called a convection current
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17
Q

Electromagnetic radiation

A

All bodies (objects) emit electromagnetic radiation

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18
Q

What does intensity & wavelength of a radiation wave depend on?

A

Temperature

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19
Q

A remote emits infrared radiation, but why won’t it burn you?

A

Because it is not intense enough

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20
Q

A toaster emits infrared radiation, but why won’t it burn you?

A

Because it is not intense enough

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21
Q

What colour does a Bunsen flame turn when it becomes hotter?

A

Blue- wavelength has decreased

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22
Q

What does iron emit at room temperature?

A

As much infrared as it absorbs & emits no visible light

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23
Q

What does iron emit when heated?

A

Visible light, because the wavelength of infrared has been reduced

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24
Q

Explain the role of convection in everyday phenomena

A

When fluids such as water in a boiler or air around a radiator, is heated:
- Hot fluid becomes less dense
- Less dense fluid rises
- Cool fluid becomes more dense

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25
Infrared (IR) radiation
- Electromagnetic wave (thus behaves like light) - Can be emitted, absorbed or reflected
26
Light, shiny surface
- Good reflector - Bad absorber - Bad emitter
27
Dark, matt surface
- Bad reflector - Good absorber - Good emitter
28
If radiation in = radiation out
- Energy does not change - Temperature does not change
29
If radiation in > radiation out
- Internal energy increases - Temperature increases
30
If radiation in < radiation ouT
- Internal energy decreases - Temperature decreases
31
PRACTICAL: investigate thermal energy transfer by conduction
Conduction 1. Attach paperclips to each rod at evenly space distances using Vaseline 2. Light the Bunsen burner, so that the rod is in the flame & start the stopwatch 3. Record the time that each of the paperclips fall off the conducting rod in a table 4. Repeat for other rods made of different materials 5. Valid- same spacing of paper clips on each rod: -same distance from the flame -same amount of petroleum jelly on each paperclip -same thickness of each material
32
PRACTICAL: investigate thermal energy transfer by convection
Convection 1. Add some potassium permanganate crystals to one side of a beaker of water 2. Using a Bunsen burner, gently heat the crystals 3. As the temperature of the beaker increases, the crystals will begin to dissolve 4. This will form a bright purple solution 5. The solution will be carried through the beaker by convection currents
33
PRACTICAL: investigate thermal energy transfer by radiation
Radiation 1. Place both the silver & black tin on a heatproof mat. Fill each tin with the same volume hot of water. (measure with measuring cylinder) 2. Start a stopwatch & record the initial temperature of the water a table 3. Record the temperature of the water every minute for 15 minutes 4. Valid- same volume of water: -same initial temperature of water
34
PRACTICAL: investigate thermal energy transfer by radiation Leslie Cube
Radiation - A Leslie Cub is a metal container with different coloured walls - Hot Water can be poured into the container & heat loss via radiation from different coloured surfaces can be studied - You can ‘see’ infrared radiation emitted from a surface using an infrared camera
35
What is a way of reducing unwanted energy transfer?
Use thermal insulation - The lower the thermal conductivity (doesn’t transfer heat very well), the more heat is insulated - The thicker the material, the more heat is insulated -> Insulators trap pockets of air, reducing the movement of fluid
36
Equation for work done:
Work done (J) = Force (N) x Distance moved in direction of force (m)
37
Work done = ?
Work done = Energy transferred
38
Equation for GPE:
Change in gravitational potential energy (J) = Mass (kg) x Gravitational field strength (m/s² or N/kg) x Change in vertical height (m)
39
Equation for Kinetic energy:
Kinetic energy (J) = ½ x Mass (kg) x (Speed)² (m/s)
40
What is the link between GPE & KE if an object falls?
GPE → KE & (change in)GPE = work done
41
What is the link between GPE & KE if an object is thrown upwards?
KE → GPE & (change in) KE = work done
42
What is power?
The amount of energy transferred every second, therefore Power is the rate of work done
43
Equation for Power:
Power (W) = Work done (J) / Time taken (s)
44
PAPER 2 Most large-scale electricity production is done using turbines, the energy transfers involved are either:
- Stored chemical or nuclear energy → - Thermal energy in high - pressure steam / Kinetic Energy of environment (wind/water) → - Kinetic energy of rotating turbine → - Electrical energy output
45
PAPER 2 Wind energy
- Energy from the wind - Wind turbines use the kinetic energy of the wind to produce electricity
46
PAPER 2 Advantages of wind energy:
- Renewable - Produces no polluting gases
47
PAPER 2 Disadvantages of wind energy:
- Noise pollution - Visual pollution - Weather dependent (windy) - Dilute source of energy - Energy generation cannot change to meet demand
48
PAPER 2 Hydroelectric energy
- Energy from rivers - The water flowing down a river has stores gravitational potential energy - which is converted to kinetic to produce electricity - We usually need to build a dam & let the water flow through it gradually
49
PAPER 2 Advantages of hydroelectric energy:
- Renewable - Produces no polluting gases
50
PAPER 2 Disadvantages of hydroelectric energy:
- Requires large dam/flooding large area - Geographical limitations (flowing water hills/mountains)
51
PAPER 2 Tidal energy
- Energy from sea tides - The sea level goes up & down, because of tides - The kinetic energy of the water is used to produce electricity
52
PAPER 2 Advantages of tidal energy:
- Renewable - Produces no polluting gasses - Reliable, because there are always two tides every day
53
PAPER 2 Disadvantages of tidal energy:
- The dam may cause local flooding - Energy generation cannot change to meet demand - Dilute source of energy
54
PAPER 2 Wave energy
- Energy from seas - The sea’s waves have kinetic energy - Using machines that bob up & down in the waves, this energy can be used to produce electricity
55
PAPER 2 Advantages of wave energy:
- Renewable - Produces no polluting gasses
56
PAPER 2 Disadvantages of wave energy
- Weather dependent (waves might not be big enough) - May cause harm to wildlife - Possible storm damage to generator
57
PAPER 2 Geothermal energy
- Energy from the Earth - Deep underground, the Earth’s rocks are naturally very hot - We can turn their thermal energy to heat water, which can be used to drive a turbine & produce electricity
58
PAPER 2 Advantages of geothermal energy:
- Renewable - Produces no polluting gasses - Doesn’t damage the environment
59
PAPER 2 Disadvantages of geothermal energy:
- Depends on geographical location (very few places in the world where you can do this) - Very difficult to drill deep into the ground
60
PAPER 2 Solar energy
- Energy from the Sun - The Earth gets thermal & light energy from the sun all the time. This energy can either be: 1. changed into electrical energy to use in homes, using solar cells; 2. or used to heat water for homes, using solar panels
61
PAPER 2 Advantages of solar energy:
- Renewable - Produces no polluting gasses
62
PAPER 2 Disadvantages of solar energy:
- Weather dependent - Does not work at night (no sun) - Requires large open spaces - Depends on geographical location
63
PAPER 2 Fossil fuels
- Oil, Coal, Natural gas - The chemical potential energy stored in things that were once alive & ae later fossilised (e.g. prehistoric life) can be burned to release their stored energy
64
PAPER 2 Advantages of Fossil fuels:
- Energy generation can change to meet demand - Reliable - Does not depend on weather
65
PAPER 2 Disadvantages of Fossil fuels:
- Releases carbon dioxide, sulphur dioxide & greenhouse gases- causes global warming - Non-renewable
66
PAPER 2 Nuclear energy
- Energy from atoms - The nuclear energy stored in the nuclei of atoms can be released by fission in a reactor
67
PAPER 2 Advantages of Nuclear energy:
- Energy generation can change to meet demand - Reliable - Does not depend on weather - Produces no polluting gasses - Very dense source of energy - Statistically safest form of energy generation
68
PAPER 2 Disadvantages of Nuclear energy:
- Radioactive waste produced - Non-renewable - Risk of nuclear accident

PHYSICS (8 decks)

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