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Energy Efficiency

The document discusses energy efficiency calculations for various systems using the formula for efficiency. It includes examples with Sankey diagrams, detailing energy transfers and the resulting efficiencies for different scenarios, such as batteries, cars, bulbs, and athletes. The efficiencies calculated range from 5% to approximately 75%, highlighting the energy losses primarily due to heating.

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am.waseem0508
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21 views2 pages

Energy Efficiency

The document discusses energy efficiency calculations for various systems using the formula for efficiency. It includes examples with Sankey diagrams, detailing energy transfers and the resulting efficiencies for different scenarios, such as batteries, cars, bulbs, and athletes. The efficiencies calculated range from 5% to approximately 75%, highlighting the energy losses primarily due to heating.

Uploaded by

am.waseem0508
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Date: 25-10-2020

Topic: Energy Efficiency Teacher: Muhammad Waseem Akram

Name _____________________________ Class ____________

Answer all the questions:

The % efficiency of a machine can be found using the following equation.

efficiency = Useful energy output x 100%

Total energy output

For the following Sankey diagrams describe in as much detail what is happening
and calculate the efficiency.

1. Chemical Energy in the battery is transferred to the bulb by electricity, and


then from the bulb to the surroundings by light.
Some energy is transferred to the surroundings by heating.

Efficiency = 5%

2. Chemical Energy in the petrol is transferred to the car as kinetic energy.

A lot of energy is transferred to the surroundings by heating.

Efficency =25%

3. Electrical Energy is transferred to the bulb, and then from the bulb to the
surroundings by light.

Some energy is transferred to the surroundings by heating.

Efficiency = 25%

4. Chemical Energy in the food is transferred to the athlete as kinetic energy.

Some energy is transferred to the surroundings by heating.

Efficiency = 20%

5. Electrical Energy is transferred to the load by the electric motor into


gravitational potential energy.

Some energy is transferred to the surroundings by heating and sound.

Efficiency = approx. 75%

6. Chemical Energy in the fuel is transferred to thermal energy by the boiler,

then transferred to kinetic energy in the turbine. This is

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