Energy- Efficiency

Question 1

______ __________ are not 100% efficient and all efficiencies exist between 0-100%.

Answer 1

Energy transfers are not 100% efficient and all efficiencies exist between 0-100%.

Question 2

Useful energy is the energy ____________ into the form of energy that is _______.

Answer 2

Useful energy is the energy transferred into the form of energy that is wanted.

Question 3

Wasted energy is when energy is transferred into a form of energy that is ___ ______.
This is often ________ store or _____ store.

Answer 3

Wasted energy is when energy is transferred into a form of energy that is not useful.
This is often thermal store or sound store.

Question 4

how is efficiency calculated (2 equations)

Answer 4

useful output energy transfer /
total input energy transfer

useful power output /
useful power input

Question 5

how can you tell if you have calculated efficiency wrong

Answer 5

if you get an efficiency greater the 1 or a percentage above 100

Question 6

how can we increase the efficiency of an energy transfer
heating hot water.

Answer 6

ensure the pan is the same size as the hob to reduce energy being transferred our into the air
add a lid to stop water escaping from the surface of the water

Question 7

why is a kettle more efficient

Answer 7

the heat source us inside the water meaning energy is not being wasted from heating the bottom of the pan
kettles are normally plastic where as a pan is metal which is a better conductor of heat and so plastic reduces heat loss