Unit 5.2--Energy Conversion Flashcards
(13 cards)
True or False
Can energy be converted from one form into another?
True
Describe the energy conversion:
When an electric toaster is switched on
Electrical energy —> thermal energy
Describe the energy conversion:
When a candle burns
Chemical energy —> light+thermal energy
Describe the energy conversion:
The process of photosynthesis which took place in plants
Light energy—> chemical energy
What is the law of conservation of energy?
Energy can be converted from one form into another but cannot be created or destroyed.
Consider the motion of a ball and explain with the law of conservation with 3 steps.
- When a ball falls to the ground, its potential energy —> kinetic energy
- When the ball reaches the ground, some of its kinetic energy—> sound + thermal energy. Thus, the ball has less energy after the bounce and cannot return to same height
- When the ball bounces up, its remaining kinetic energy—> potential energy
What is the purpose of a Sankey diagram?
To show an energy conversion process
State the conversion of energy when a light bulb is lit.
Electrical energy —> thermal+ light energy
True or False:
Energy can be created in a power station.
False
What are energy converters?
Devices or appliances to convert energy from one form into another form of useful energy
What is the efficiency of an energy converter?
A measure of how much energy input is converted into useful energy output
What is the formula the calculate the efficiency of an energy converter?
Efficiency= Useful energy output
————————— x 100%
Total energy input
Calculate the efficiency of the following:
An electric fan sues 50J of electrical energy and 20J into thermal energy.
Efficiency= 30
—— x100%
50
=60%
