Energy resources and transfers Flashcards
The lamp has an efficiency of 20%
explain what this means
- 20% of the energy input
- 20% is transferred usefully
Suggest why the ball traveled further on the Moon than it would have done on Earth.
- Less gravity
- Lack of air resistance
Why is the amount of GPE gained by the mass less than the amount of electrical energy transferred to the motor?
- Energy is lost as heat
- The mass has gained KE
Explain how the current produces movement of the coil
- Current in coil
- Creates a magnetic field
- There is a force on the wire
- Force up one side and down on other side
Describe the energy changes that take place in the lamps when they are connected to the power supply
- electrical
- to light
Explain how the woolen blanket helps to keep the student warm
- Air stops conduction
- Blanket is an insulator
- Air is trapped
- Sweat cannot be evaporated
Explain why only some of the GPE of the mass is transferred to the lamp.
- to overcome friction
- not 100% efficient
Water from a reservoir can be used to generate electricity on a large scale. Describe the energy transfers involved in this process.
- Electrical energy is produced
- KE of moving water
- Work done on the turbine generator
Explain how this type of insulation reduces energy loss by conduction
- Air is a bad conductor because air particles are widely separated.
- Conduction requires solids
Discuss what information the image gives about the temperature of the objects shown
- Bear’s fur and snow are about the same temperature
- Bear’s nose is warmer than the fur
Explain how its fur reduces the amount of thermal energy is lost by the polar bear
- Air is an insulator
- Air is trapped near the body by fur
Discuss how these colours affect the overall amount of thermal energy lost by the polar bear’s body
- 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)
Compare the absorption and reflection of UV rays by the objects shown in the image.
- Snow reflects UV
- Bear’s fur absorbs UV
Suggest why the sky appears dark, even though the Sun emits UV rays
- Sky absorbs the UV
Suggest why this radiation does not pass down to the polar bear’s skin.
- UV is absorbed by hair
- Light travels in air
Describe the energy transfers at each stage of electricity generation from this resource.
- 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
Explain what happens to the air at A just under the cover
- Becomes less dense
- Air heats up
- Air rises
Describe how a SUT can be used to generate electricity
- Hot air turns turbines
- Turbines turn the generator
Suggest why the SUT generates most electricity during daylight hours
There is direct heating from the sun
Suggest why there are blocks of material that absorb thermal radiation in the SUT
To act as a heat source for night time.
Suggest an alternative to these blocks that would improve the total energy output of the SUT
Water tanks
Describe how energy is transferred from the hot plate to heat up all of the potato.
- Conduction from the hot plate to pan
- Conduction from the water to the potato
- Convection in the water
- Conduction through potato
Explain whether this statement is true by describing how energy is transferred to heat up all of the potato.
- Electromagnetic waves penetrate into the food which causes the water molecules to vibrate more which leads to conduction through the rest of the potato
Describe how energy is transferred to heat up all of the potato
- 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
