lesson 10 — 1st online lesson

2.10 Energy

calculation's

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Slide 1: Slide

energy calculationsVoortgezet speciaal onderwijsLeerroute 1

This lesson contains 19 slides, with interactive quizzes and text slides.

Items in this lesson

2.10 Energy

calculation's

Slide 1 - Slide

Learning goals

Give examples of useful energy and wasted energy

Explain what is meant by efficiency

Be able to do calculations that involve energy

Slide 2 - Slide

Useful energy

wasted energy

Efficiency

Slide 3 - Slide

Useful energy

The amount of joules that do the work you want

Wasted energy

The amount of joules that do work that you don't want

Efficiency

The percentage of the total energy input that gets converted into useful energy.

Slide 4 - Slide

The efficiency of a construction lamp

A construction lamp uses 80 joules/second

It produces 20 J of light energy per second.

It produces 60 J of thermal and sound energy per second.

Slide 5 - Slide

The efficiency of a construction lamp

Slide 6 - Slide

The efficiency of a construction lamp

Slide 7 - Slide

Useful

The efficiency of a construction lamp

Slide 8 - Slide

Useful

Wasted

The efficiency of a construction lamp

Slide 9 - Slide

E f f i c i e n c y = (\frac{​ u s e f u l e n e r g y ​ ​}{​ t o t a l e n e r g y ​}) \cdot 100

Slide 10 - Slide

E f f i c i e n c y = (\frac{​ u s e f u l e n e r g y ​ ​}{​ t o t a l e n e r g y ​}) \cdot 100

= (\frac{​ E ^{​ u ​ ​} ​ ​}{​ E ^{​ t ​ ​} ​}) \cdot 100

η: efficiency (%)
Eu: Energy useful (J)
Et: energy total (J)

Slide 11 - Slide

The efficiency of a construction lamp

Slide 12 - Slide

Calculate the efficiency of the lamp of this energy transformation diagram

Given:

Total energy = 80 Joule
Useful energy = 20 J

Asked:

Calculate the efficiency of this lamp

Formula:

Calculation:

Slide 13 - Slide

Calculate the efficiency of the lamp of this energy transformation diagram

Given:

Total energy = 80 Joule
Useful energy = 20 J

Asked:

Calculate the efficiency of this lamp

Formula:

Calculation:

E f f i c i e n c y = (\frac{​ u s e f u l e n e r g y ​ ​}{​ t o t a l e n e r g y ​}) \cdot 100

Slide 14 - Slide

Calculate the efficiency of the lamp of this energy transformation diagram

Given:

Total energy = 80 Joule
Useful energy = 20 J

Asked:

Calculate the efficiency of this lamp

Formula:

Calculation:

E f f i c i e n c y = (\frac{​ u s e f u l e n e r g y ​ ​}{​ t o t a l e n e r g y ​}) \cdot 100

E f f i c i e n c y = (\frac{​ 2 0 ​ ​}{​ 8 0 ​}) \cdot 100

= 25

Slide 15 - Slide

A certain light bulb uses 200 J of electrical energy.

It produces 20 J of light energy.

Calculate its efficiency

10 %

20%

40%

Slide 16 - Quiz

These fairy lights use 230 J of electrical energy and produce 92 J of light energy. Calculate their efficiency

20 %

25%

60%

Slide 17 - Quiz

Total energy = 1000000J

Useful energy = 650000J

Calculate the efficiency of this airplane.

50%

65%

35%

80%

Slide 18 - Quiz

Learning goals

Give examples of useful energy and wasted energy

Explain what is meant by efficiency

Be able to do calculations that involve energy

Slide 19 - Slide

lesson 10 — 1st online lesson

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§4 Efficiency

Efficiency