Energy Efficiency and Sankey Diagrams

The video tutorial explains the concept of Sankey diagrams, which are used to visualize energy efficiency in a graphical manner. It compares the energy efficiency of filament lamps and energy-saving lamps, highlighting how energy is used and wasted. The tutorial also covers calculations of energy in watts and joules, and applies these concepts to analyze the energy efficiency of a car. The importance of understanding energy flow and conservation is emphasized throughout.

What is the primary purpose of a Sankey diagram?

• To calculate the cost of energy

• To show the flow of energy in a system

• To determine the color of light emitted

• To measure the speed of energy transfer

In a Sankey diagram, what does a larger branch represent?

• The speed of energy transfer

• The color of the energy source

• Less energy being used

• More energy being used

What percentage of energy is used as light in a filament lamp according to the example?

• 10%

• 20%

• 80%

• 50%

How does the conservation of energy principle apply to Sankey diagrams?

• Energy can be created or destroyed

• Energy is always lost in the system

• Energy is always converted into light

• Energy cannot be created or destroyed, only converted

If a lamp uses 50 watts of power, how many watts are used as light if it is 20% efficient?

• 40 watts

• 20 watts

• 5 watts

• 10 watts

In the car example, how much energy is converted into kinetic energy?

• 120 joules

• 130 joules

• 350 joules

• 600 joules

What is the total energy input for the car in the example?

• 350 joules

• 250 joules

• 600 joules

• 120 joules

How much energy is wasted as heat in the car example?

• 600 joules

• 350 joules

• 130 joules

• 120 joules

What is the formula for calculating efficiency?

• Useful energy out divided by total energy in

• Total energy in divided by useful energy out

• Total energy out divided by useful energy in

• Useful energy in divided by total energy out

What is the efficiency of the car in the example?

• 80%

• 20%

• 50%

• 10%