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Energy Transfer Flashcards

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0
Q

What are the energy changes that take place in a kettle

A

Electric –> heat + sound

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1
Q

What are the energy changes that take place in a motor

A

Electric –> kinetic energy + heat + sound

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2
Q

What are the energy changes that take place in a rechargeable battery

A

Chemical –> electric + heat

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3
Q

What are the energy changes that take place in a person walking up a flight of stairs

A

Chemical –> k.e + g.p.e. + heat + sound

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4
Q

What are the energy changes that take place in a pendulum swinging back and forth

A

Gpe–> ke –> gpe –> ke ………

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5
Q

Name a device in which the following energy changes take place:
Light –> chemical

A

Photosynthesis

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6
Q

Name a device in which the following energy changes take place:
Light –> electrical

A

Solar cells/panels

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7
Q

Name a device in which the following energy changes take place:
Electrical –> sound

A

Speaker

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8
Q

Name a device in which the following energy changes take place:
Sound–> electrical

A

Microphone

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9
Q

Name a device in which the following energy changes take place:
Gpe –> ke

A

Pendulum on its downward swing

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10
Q

Define energy

A

Objects with energy have the ability to work on other objects which makes things happen. In doing so, energy changes from one form to another.

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11
Q

List the different forms of energy

A 
Kinetic energy 
Potential energy 
Chemical energy 
Thermal energy 
Light energy 
Sound energy 
Electrical energy 
Nuclear energy
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12
Q

What is the production of heat light and sound often referred to as?

A

Undesirable energy. In any energy change you always get some wasted energy produced. This is usually in the form of heat, light or sound.

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13
Q

The principle of conservation of energy

A

Energy cannot be created or destroyed, but can be changed from one form to another.

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14
Q

Name 4 experiments for conduction

A

1) Inge-haaze
2) wood, brass & paper
3) Bunsen burner and match
4) boiling tube with ice at one end and boiling water at the other.

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15
Q

Explain the Inge haaze experiment

A
  • we filled a box with boiling water
  • it’s that coming out of the box are made of different metals
  • The pins are stuck on with wax
  • The metal rods that is the best conductor will melt the wax the quickest, making the pin fall off
  • copper was the quickest, then Aluminium
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16
Q

Explain the experiment involving a brass stick and they wood stick with a piece of paper covering to the joint.

A
  • The piece of paper is covering the joint of the brass stick and the wood stick
  • we hovered it over a flame
  • Only half of the paper blackened, that was the half on the wood stick
  • this is because the brass conducted the heat away from the paper, therefore preventing the paper from blackening
  • brass is a good conductor, as it could conduct the heat away. Wood is not a good conductor and could not conduct the heat away so the paper got burnt
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17
Q

Explain the experiment that displays conduction with a Bunsen burner and match

A
  • we held the match at different distances from the Bunsen burner
  • The match only burnt when it was 1 cm away from a 9500°C flame
  • This shows us gas is not a good conductor
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18
Q

Explain the experiment that displays conduction involving the boiling tube with ice and a Bunsen burner

A
  • We put ice at one end of a boiling tube and gently heated the other and with a Bunsen burner.
  • The ice stayed as ice, while the top was boiling.
  • Water is a bad conductor
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19
Q

Explain the structure of a solid. and what happens to it when it is heated

A
  • And solids, particles form a 3D lattice structure
  • particles can VIBRATE but NOT move around
  • When a solid is heated, its particles vibrate more
  • this causes them to collide with neighbouring particles. Each collision shares kinetic energy between the two particles
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20
Q

Define conduction

A

Conduction is the transfer of energy with no overall transfer of matter

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21
Q

Explain and describe the structure of a metal

A
  • Metals have delocalised electrons

- When metals are heated the electrons gain kinetic energy and collide with others, sharing their kinetic energy

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22
Q

Describe the structure of liquids and gases

A
  • In liquids and especially gases, the particles are further apart than in solids.
  • When heated, they have more kinetic energy
  • Collisions result in the energy being shared
23
Q

In general, what are good conductors and what are bad conductors?

A

Metals are good while nonmetals are poor

24
Q

List these according to how well they conduct energy:

Gold, silver, aluminium, iron, copper, lead

A 
Best conductor of energy
1.silver
2.copper
3.gold
4.aluminium
5.iron
6.lead
Worst conductor of energy
25
Q

What are two examples of good insulators

A
  1. A vacuum is the best-no energy can pass through a vacuum by conduction or convection (energy can only pass through a vacuum by radiation)
  2. The next best insulator is a hyphen very little energy can pass through there by conduction
26
Q

Explain what happens in the convection

A
  1. Part of a substance (liquid or gas only) is heated.
  2. particles in a substance gain kinetic energy and move around faster. Making them spread out-the substance expands
  3. This makes the hotter substance less dense than the cooler substance
  4. The hotter, less dense substance rises
  5. Cooler, denser substance replaces the hottest substance which has risen. It then starts again from number one
27
Q

Name to convection demonstrations

A

A mine with two chambers, and a circular tube filled with water

28
Q

Explain the demonstration of convection involving the circular tube filled with water.

A
  • We put purple dye into a circular tube filled with water
  • We heated the bottom right corner
  • as the water is heated, it becomes less dense ( because the water molecules get further apart) and rises, pushing the water and dye around the tube anti clockwise
  • Cooler, denser water replaces the water which has risen
29
Q

Explain the demonstration of convection including the mine with two chambers

A
  • The air at the bottom of the mine is old, say they light a fire by one entrance.
  • This makes the air by the fire less dense, so it rises reducing the pressure in the mine, causing clean air to be drawn in through the other entrance
30
Q

Give two examples of convection uses in the household and explain them

A
  1. The radiator- radiators heat by convection rather than radiation. Warm air is drawn in, the warm air then rises, cooler then drops and replaces the warm air that is then drawn in to the heater
  2. Heating water in a pan - we get conduction of the heat through the metal which heats the water at the bottom. Allowing convection current to form in the water
31
Q

Explain how a hot water system works

A
  • The boiler is always below the hot water storage tank
  • Hot water for taps always comes from the top of the tank to ensure we get the hottest possible water from the tank
  • Hot water rises by convection from the boiler to the storage tank
  • The water which has cooled will sink to the bottom of the storage tank and go to the boiler to be heated again and will rise back up
32
Q

Define convection

A

Convection is the transfer of energy from one place to another by the movement of the heated material itself.

33
Q

Where can convection occur

A

In liquids and gases only- NOT IN SOLIDS

34
Q

Explain why the heating element of an electric kettle is placed near the bottom.

A

When the kettle is switched on, The water around the heating element is heated by the heating element. Because of convection, the warmer water will rise and the cooler water sinks. The heating element must be placed at the bottom so the cold water that sinks can be heated. In this way, all the water gets heated up by convection until it boils.

35
Q

Explain how convection causes land and sea breezes.

A
  • During the day the land heats up faster than the sea. The air above the land is also heated up and rises. The cooler air over the sea blows in as a sea breeze to replace the air that has risen.
  • At night the land cools faster than the sea. The sea is warmer than the land and the air above the sea rises. The cooler air over the land blows out as a land breeze and replaces the rising air
36
Q

Does radiation involve particles

A

No

37
Q

What do all objects both emit and absorb

A

Infra-red radiation

38
Q

What does the amount of radiation emitted depend on

A

1) The surface area of an object
2) the temperature difference between the object and surroundings
3) The colour/texture of the surface e.g. dull black or shiny silver

39
Q

What colour/texture is the best and worst emitter/absorber of radiation

A

Dull black is the best at emitting and absorbing

Shiny silver/white is the worst as they reflect radiation

40
Q

Describe how the following features on a vacuum flask keep food hot or cold:
Plastic stopper

A
  • Stop or reduce energy loss by convection as it obstructs the convection currents
  • The plastic will stop or reduce energy loss by conduction because plastic is a bad conductor of heat.
41
Q

Describe how the following features on a vacuum flask keep food hot or cold: vacuum

A

-Stops energy loss by conduction or convection (there aren’t any particles so the convection and conduction cannot happen as they need particles)

42
Q

Describe how the following features on a vacuum flask keep food hot or cold: thin silvered walls

A
  • Reflects any radiation from the hot drink back in

- and any radiation from the outside will be reflected back out

43
Q

How is a refrigerator insulated to prevent heat from entering

A
  • Building insulating materials inside the refrigerator in walls-cuts down heat entering by conduction
  • installing magnetic strip around the door to form a tight seal when the door is closed-prevents heat from the outside entrance by convection
44
Q

Why is the freezer always placed on top inside of fridge

A

This allows convection currents to cool down the refrigerator

  • The air around the freezer is cooled and sinks
  • The cold air cools the food in the compartment below
  • As a result, the air becomes less cold and rises
  • Thus there is convection inside a refrigerator
45
Q

Define radiation

A

Radiation is the transfer of energy through a vacuum in the form of electromagnetic waves

46
Q

Explain where conduction, convection and radiation come from

A

Conduction through a substance
Convection in a substance
Radiation emitted from a surface

47
Q

How does loft installation help insulates do you home

A

The glass fibre forms a criss-cross. Air gets trapped between the fibres.

  • This reduces conduction (air /glass are poor conductors)
  • Reduces convection (air trapped)
48
Q

Explain how draft excluder’s help insulates the home

A
  • Two bits of spans connected by a bit of material that goes under the door to stop drafts
  • Plugging the gaps reduces the movement of air.
49
Q

Roughly where does the heat escape from in our homes

A
  • 25% in the roof
  • 35% from the walls
  • 10% from the windows
  • 15% from drafts
  • 15% from floors
50
Q

Explain how cavity wall installations help insulate our homes

A
  • In many houses there is a cavity between two layers of brick
  • this means that convection current happen in this cavity
  • To stop the use they can either:
    1) drill a hole into the cavity and fill it with foam. The foam expands and sets and therefore traps the convection currents
    2) when building a new house, you build with breeze blocks that have foam attached in the holes. This again traps the air to stop convection current
51
Q

How can double glazing help insulate the home

A
  • With either at between the panes or almost vacuum between
  • The vacuum is better because conduction and convection can’t happen
  • With their convection and conduction is reduced but not eliminated
  • very expensive
52
Q

How can carpets and carpet underlay help insulates the home

A
  • the air gets trapped in the fibres and so helps reduce conduction
  • The extra layer of underlay taps more air.
53
Q

What is cost efficiency?

A

Cost efficiency is the amount of profit or loss you have made over a certain amount of time when you consider the initial outlay and annual saving
(Annual cost X years)-cost

54
Q

What is payback time

A

Payback time is the number of years it takes to cover the initial outlay
Cost/savings

Physics (12 decks)

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