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Physics > Energy resources and transfers > Flashcards

Energy resources and transfers Flashcards

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1
Q

The lamp has an efficiency of 20%

explain what this means

A
  • 20% of the energy input
  • 20% is transferred usefully
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2
Q

Suggest why the ball traveled further on the Moon than it would have done on Earth.

A
  • Less gravity
  • Lack of air resistance
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3
Q

Why is the amount of GPE gained by the mass less than the amount of electrical energy transferred to the motor?

A
  • Energy is lost as heat
  • The mass has gained KE
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4
Q

Explain how the current produces movement of the coil

A
  • Current in coil
  • Creates a magnetic field
  • There is a force on the wire
  • Force up one side and down on other side
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5
Q

Describe the energy changes that take place in the lamps when they are connected to the power supply

A
  • electrical
  • to light
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6
Q

Explain how the woolen blanket helps to keep the student warm

A
  • Air stops conduction
  • Blanket is an insulator
  • Air is trapped
  • Sweat cannot be evaporated
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7
Q

Explain why only some of the GPE of the mass is transferred to the lamp.

A
  • to overcome friction
  • not 100% efficient
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8
Q

Water from a reservoir can be used to generate electricity on a large scale. Describe the energy transfers involved in this process.

A
  • Electrical energy is produced
  • KE of moving water
  • Work done on the turbine generator
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9
Q

Explain how this type of insulation reduces energy loss by conduction

A
  • Air is a bad conductor because air particles are widely separated.
  • Conduction requires solids
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10
Q

Discuss what information the image gives about the temperature of the objects shown

A
  • Bear’s fur and snow are about the same temperature
  • Bear’s nose is warmer than the fur
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11
Q

Explain how its fur reduces the amount of thermal energy is lost by the polar bear

A
  • Air is an insulator
  • Air is trapped near the body by fur
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12
Q

Discuss how these colours affect the overall amount of thermal energy lost by the polar bear’s body

A
  • Black (skin) is a good emitter
  • White fur is a good reflector of thermal energy
  • the reflected thermal energy is absorbed by the black (skin)
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13
Q

Compare the absorption and reflection of UV rays by the objects shown in the image.

A
  • Snow reflects UV
  • Bear’s fur absorbs UV
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14
Q

Suggest why the sky appears dark, even though the Sun emits UV rays

A
  • Sky absorbs the UV
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15
Q

Suggest why this radiation does not pass down to the polar bear’s skin.

A
  • UV is absorbed by hair
  • Light travels in air
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16
Q

Describe the energy transfers at each stage of electricity generation from this resource.

A
  • Thermal energy is transferred from the hot rocks to the cold water
  • This leads to water molecules gaining KE
  • Steam gains KE as it is heated by the rock
  • GPE of steam increases as it gains height
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17
Q

Explain what happens to the air at A just under the cover

A
  • Becomes less dense
  • Air heats up
  • Air rises
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18
Q

Describe how a SUT can be used to generate electricity

A
  • Hot air turns turbines
  • Turbines turn the generator
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19
Q

Suggest why the SUT generates most electricity during daylight hours

A

There is direct heating from the sun

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20
Q

Suggest why there are blocks of material that absorb thermal radiation in the SUT

A

To act as a heat source for night time.

21
Q

Suggest an alternative to these blocks that would improve the total energy output of the SUT

A

Water tanks

22
Q

Describe how energy is transferred from the hot plate to heat up all of the potato.

A
  • Conduction from the hot plate to pan
  • Conduction from the water to the potato
  • Convection in the water
  • Conduction through potato
23
Q

Explain whether this statement is true by describing how energy is transferred to heat up all of the potato.

A
  • Electromagnetic waves penetrate into the food which causes the water molecules to vibrate more which leads to conduction through the rest of the potato
24
Q

Describe how energy is transferred to heat up all of the potato

A
  • Coil creates magnetic field around it which cuts through the metal pan
  • field changes
  • Causing a current in the pan
  • Current makes the pan get hot
  • which heats the water by conduction
25
Q

Use information from the diagrams and bar charts to describe what happens to the energy, speed and position of the ball as it vibrates on the spring

A
  • KE is the greatest in the middle
  • GPE is least at the bottom
  • EPE is greatest at the bottom
  • The change in KE is 4J
  • Change in EPE > change in KE
  • Total energy is constant
26
Q

Describe two ways that the student can make the pointer move to the right.

A
  • Reverse the magnetic poles so its facing North
  • Move the magnet out of coil
27
Q

Explain how an object becomes charged by friction

A
  • Rubbing of surfaces
  • Electrons have negative charge
  • Transferring of electrons
28
Q

Explain why the end of the tape moves back towards the roll

A
  • There are opposite charges
  • An attractive force is larger than the weight of the loose end of the tape
29
Q

Give an example of a non-renewable energy source

A

Coal, Oil, Gas

30
Q

Explain how the electrical energy from a remote wind farm is transmitted to large cities

A
  • Transmitted at high voltage and low current
  • No energy is wasted during transmission
  • Voltage increased for transmission
31
Q

Discuss the advantages and disadvantages of building more wind farms

A

ADVANTAGES:

  • Renewable
  • No carbon emissions
  • Source of energy is free
  • Wind farm can generate large amounts of electricity

DISADVANTAGES:

  • Ugly-looking
  • Causes noise pollution
  • only works when wind blows
  • Costly to construct
32
Q

The suitcase falls over.

Explain why it loses GPE when it falls

A
  • GPE depends on the height
  • Height has reduced
33
Q

Explain how evaporation cools the water

A
  • Temperature proportional to average KE
  • Particles leave the surface
  • Highest energy particles leave the liquid
34
Q

Use ideas about particles to describe the changes that happen when a liquid boils to form a gas

A
  • Particles move apart
  • Particles gain KE
  • Particles move freely
35
Q

Explain how the shiny surfaces reduce the thermal energy transferred to the liquid oxygen from the laboratory

A
  • Poor emission
  • No absorption
36
Q

Explain how the vacuum reduces the thermal energy transferred to the liquid oxygen from the laboratory

A
  • IN a vacuum there are no particles

-Poor conduction

37
Q

Dewar’s flask did not have a lid when it was holding liquid oxygen

Suggest why a lid was not needed

A
  • Oxygen in the room is warmer
  • Convection currents in air
38
Q

Using only information in the table, evaluate which types of power station would be the most suitable to meet this increased demand

A
  • Wind
  • Gas
    -Tidal
    -Nuclear
    -Coal
39
Q

Explain how location and the climate might affect the type of power station that the company chooses

A

LOCATION:

  • Suitability of site
  • Geological factor
  • Sun angle
  • Proximity of population

CLIMATE:

  • Effect of seasons
  • hours of sunlight
  • intensity of sunlight
  • Geothermal power station is not affected by climate
40
Q

Explain why wind turbines have not replaced them

A
  • Site choice
  • Unreliability
  • Cost
  • Environmental effects
41
Q

State one advantage of transmitting electricity at high voltages

A
  • Less power losses
42
Q

Describe the problems that arise from the disposal of waste from this type of power station.

A
  • Radioactive
  • High activity
  • Danger
  • Need for security
43
Q

Define the relationship between work done, force, and distance moved

A

Work done (J) = Force (N) × distance moved (m).

44
Q

What is the formula for efficiency?

A

Efficiency = (useful energy output / total energy output) × 100%.

45
Q

List the advantages and disadvantages of using fossil fuels for large-scale electricity production

A

Advantages:
- Reliable energy production
- Can produce large amounts of energy at short notice

Disadvantages:
- Produces significant greenhouse gases and pollution

46
Q

Explain how thermal radiation transfers energy and give an example.

A

Thermal radiation is the transfer of energy by infrared waves. An example is the heat from the sun reaching the Earth

47
Q

What is the relationship between work done and energy transferred

A

Work done = energy transferred

48
Q

How can unwanted energy transfer be reduced, and give an example?

A

Insulation using poor conductors with trapped air, such as foam or glass fiber, reduces heat transfer by conduction and convection.

Physics (6 decks)

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