WHY IS ENERGY TRANSFER NOT 100 EFFICIENT

This chapter follows on from the last chapter wright here we discussed that warmth can be "lost" as power is transferred to the surroundings. This chapter now defines that within a mechanism, there is advantageous power which is transferred to the preferred object or location, yet no procedure is 100% efficient. Energy have the right to be transferred to the surroundings fairly than to the object or component of the system that you want it to transport to. This is considered a waste of power and also devices are designed to try minimize this waste so that they are even more reliable. There is always some loss of power (wasted energy) and so there are always byproducts to energy manufacturing. Several of the spin-offs are harmful to the atmosphere.

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Important to note is that CAPS provides the complying with statement:

"The output energy in a system is constantly much less than the input energy, bereason some of the energy escapes to the environment."

This is not correct as the output energy is constantly equal to the input power as power is conserved within systems. The statement have to fairly state:

"The output energy in a device is always less than the input power, bereason some of the power escapes to the setting."

The wasted power is still part of the output power from the system, it is simply not useful.

1.1 Useful and "wasted" energy (3 hours)

Tasks

Skills

Recommendation

Activity: Useful outputs from power systems

Accessing and recalling information, identifying and classifying

Suggested

Activity: Energy transfers in systems

Accessing and recalling indevelopment, identifying and classifying

CAPS suggested

Activity: Drawing Sancrucial diagrams

Interpreting, sorting and also classifying, communicating indevelopment graphically

Suggested

Activity: Relooking power transfers

Researching, accessing and recalling indevelopment, interpreting, sorting and classifying, connecting information; written, graphically

CAPS suggested


What type of useful energy output execute some units produce? What is expected by "wasted" energy? What is a Sancrucial diagram? How perform we draw Sanvital diagrams?

Useful and wasted energy


Sanessential diagram input output
The learners will certainly not have actually seen Sanessential diagrams prior to. You have to define the usefulness of representing processes making use of images. Illustrations make a quick, visual impact on the viewer which renders it easier to understand also a process. A Sanvital diagram is a visual representation of an energy procedure mirroring the input power and the output energy. Sanvital diagrams need to be attracted nicely and also as close to range as possible. Take the moment to attract a number of examples on the board so that the learners watch that all energy procedures have actually more than one output power type.


This term we have been looking at energy transfers within systems. Equipment have an input energy and an output power. Solution such as appliances, tools, vehicles and makers administer us with a valuable output. Let"s look at some examples to determine what these outputs are in some units.


Useful outputs from energy devices

INSTRUCTIONS:

Look at each of the photos and also recognize what is valuable to usage from this device.

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An electrical fan.http://www.flickr.com/photos/_wick/5861380711/

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An electrical iron.

System

What beneficial output does it administer us with?

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A light bulb.http://www.flickr.com/photos/nikonfilm35/4209619566/


System

What advantageous output does it provide us with?

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A light bulb.http://www.flickr.com/photos/nikonfilm35/4209619566/

Light

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An electric fan.http://www.flickr.com/photos/_wick/5861380711/

Movement

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An electrical iron.

Thermal energy


What was the input for each of these systems?


Electricity/electric power.


Whenever we use an appliance or a device we are transferring energy from one object to an additional. Not all the power is transferred wbelow we want it, the majority of it is transferred to the surroundings wbelow it does not aid us achieve our intends. The energy which is transferred to the surroundings is "wasted".


Watch exactly how this cacao rablittle bit melts beneath an energy-ineffective light bulb.


We deserve to usage a Sanessential diagram to present exactly how the energy is moved in a system. This provides us a snapshot of what is happening and also reflects the input power and exactly how the output power is consisted of of valuable power (arrowhead at the top) and wasted power (arrowhead going to the bottom). Have a look at the adhering to general instance.

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Sanvital diagrams are named after the Irish Captain Matthew Sancrucial, who first provided this form of diagram in 1898 in a publication on the energy effectiveness of a heavy steam engine.


The width of the arrows tell us somepoint in these diagrams. The input energy is the width of the original arrowhead. The width of both the output energy arrows (valuable and also wasted) add as much as the width of the input arrow. Why execute you think this is so? Think back to what you learned about power within units in Chapter 2.


This is because energy is neither created nor ruined, but conserved within a device. So the input need to equal the output power in a system.


Sankey diagrams are drawn to scale so that the width of the arrows offers us a visual idea of just how a lot energy is valuable and exactly how a lot is wasted. In the diagram over, you have the right to check out that only a tiny component of the input energy was valuable and a large amount of the input was wasted by being moved to the surroundings. An effective device is one wright here the advantageous output power is just slightly smaller than the input power. An inreliable mechanism has actually the majority of wasted energy. Do you think this is an effective energy system? Why?


No, it is not effective as the majority of the energy is wasted.


This brings us to our following point of exactly how efficient an power device is. If the wasted energy is much bigger than the helpful energy output, then the system is not energy effective. The over Sanvital diagram actually reflects the power transfers for a light bulb. You figured out the useful energy output as light in the last task. What carry out you think the wasted power output is? Wbelow does it go?


It is lost as heat, as power is transferred to the surrounding air.


Do you watch that an incandescent light bulb is actually not a very reliable system? This is because many the energy is lost as heat as power is transferred to the surroundings. Is tright here somepoint more efficient? Look at the photo of a fluorescent light bulb.

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A fluorescent light bulb.

A fluorescent light bulb is much more effective than incandescent light bulbs which usage a heated wire to create light. Most of the power is shed as it is transferred to the bordering air from the metal filament. In a fluorescent light bulb, much less power is lost to the surroundings and even more energy is transferred to useful light power. Use this information to attract a Sancrucial diagram for a fluorescent light bulb in the room listed below.


Learner"s diagram need to look as follows:

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Let"s look at an additional example. Look at the lady in the photo using an electric drill. The electric energy from the drill is moved to the drill little bit as kinetic energy. The drill bit turns and also drills into the steel. But the drill likewise provides many noise. Energy is provided to make sound and also the drill bits acquire warm, so some of the power is converted into thermal energy. This means that some of the electric energy has been transferred to the surroundings as sound and also thermal power. This is power that has been "wasted" bereason the sound and also thermal energy are not valuable to us.

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A lady making use of an electrical drill to make a hole in an aeroairplane component.

Complete the complying with Sanvital diagram by writing in what the energy input is, and also then the energy outputs.

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Learner"s Sancrucial diagram have to look as adheres to with the labels:

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In order to attract a Sankey diagram you must think very closely around the input power and also just how the input power is transferred to the surroundings. Let"s exercise this a little more in the adhering to task.


Energy transfers in units

INSTRUCTIONS :

Look at the complying with diagrams/photos of appliances. Complete the tables mirroring the power transfers for each diagram/photo. The first one has been completed for you.
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Filament in a light bulb.

Energy INPUT

Useful Energy OUTPUT

Wasted power OUTPUT


Energy INPUT

Useful Energy OUTPUT

Wasted energy OUTPUT

electricity

light

thermal energy


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Burning candles.
Energy INPUT

Useful Energy OUTPUT

Wasted energy OUTPUT


Energy INPUT

Useful Energy OUTPUT

Wasted energy OUTPUT

potential power in wax

light

thermal energy


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An electric beater.
Energy INPUT

Useful Energy OUTPUT

Wasted energy OUTPUT


Energy INPUT

Useful Energy OUTPUT

Wasted power OUTPUT

electricity

movement/kinetic energy

sound, thermal energy


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A auto engine.
Energy INPUT

Useful Energy OUTPUT

Wasted power OUTPUT


Energy INPUT

Useful Energy OUTPUT

Wasted power OUTPUT

petrol/potential power from burning fuel

kinetic energy

thermal energy, sound


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Welding steel together.
Energy INPUT

Useful Energy OUTPUT

Wasted energy OUTPUT


Energy INPUT

Useful Energy OUTPUT

Wasted power OUTPUT

electrical energy

thermal energy

light, sound


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Athletes running.
Energy INPUT

Useful Energy OUTPUT

Wasted energy OUTPUT


Energy INPUT

Useful Energy OUTPUT

Wasted energy OUTPUT

potential energy in food

kinetic energy

thermal power, sound


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A tv.
Energy INPUT

Useful Energy OUTPUT

Wasted energy OUTPUT


Energy INPUT

Useful Energy OUTPUT

Wasted power OUTPUT

electrical energy

light, sound

thermal energy


Now that we have established the energy transfers in each mechanism and also the input and also output power, let"s exercise illustration some even more Sankey diagrams.


Video on drawing a basic Sankey diagram.


Drawing Sanvital diagrams

Let"s look at the instance of a filament light bulb to draw a Sanvital diagram. A filament light bulb just supplies about 10101010101010101010% of the input energy to geneprice light, the rest is "wasted" because it warms up the bordering air without developing any type of light. This suggests that our Sanessential diagram should separation right into 2 parts: one for the light and also one for the thermal energy which is moved to the surroundings (heat). The thermal power arrow have to be 90% of the width of the input arrowhead and also the light arrow should be 10% of the width of the input arrow.

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INSTRUCTIONS:

Now draw a Sancrucial diagram for some of the appliances from the last activity, which are noted listed below. A description of the power transfers has been gave for each appliance. Concentprice on showing just how the input power is separation between beneficial energy and wasted power. Remember that the width of the arrow must display how much energy is moved. A thick arrowhead indicates a big amount of power, a thin arrowhead suggests a small amount of power. Show the miscellaneous input and output energies and the percentperiods.

Electric beater:

The electric beater transfers 70% of the input power to kinetic energy to beat the food and 30% is wasted output energy in the form of thermal energy and sound.

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Car engine:

The automobile engine transfers just 30% of the input energy to relocate the auto and 70% is wasted as sound and thermal power.

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Television:

The tv uses 80% of the input energy to develop the imperiods on the display screen and sound and 20% is wasted as thermal energy.

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QUESTIONS:


This is a study activity. If your learners have accessibility to the internet and/or a library then permit them to spend some time researching the energy transfers in a power plant and a vehicle engine. If your learners execute not have actually accessibility to the internet then it would certainly be an excellent concept to print out some indevelopment from miscellaneous websites that deserve to be handed out to the course. You might let the printed indevelopment circulate through the course so that you carry out not need as many kind of copies. This will certainly conserve on paper and printing expenses.

In this activity, they will certainly first check out exactly how the wasted power have the right to be in even more than one form and also exactly how to represent this in a Sankey diagram for a automobile engine. Learners will then study a power plant. You have the right to gain the learners to work in groups to find the indevelopment but make sure that each learner is able to create their own paragraph. This will certainly give you a sense of whether or not the learner has understood what they have actually researched.

Here is a resource for reference: http://www.bbc.co.uk/schools/gcsebitesize/science/21c_pre_2011/energy/generatingelectricityrev4.shtml


In our previous Sankey diagrams, we just had one arrowhead for wasted energy output, yet it can split into more than one arrow to represent the different means in which energy is wasted. There could also be more than one arrowhead for the beneficial power, for example in the TV diagram over, light and also sound are both helpful and also can be represented by two arrows.


In the last activity we looked at the energy transfers in a auto engine. However, we only used one arrow to reexisting the wasted power. We deserve to show a difference in between the methods in which power is wasted in a Sankey diagram. Use the complying with indevelopment to label the Sanessential diagram:

The input power in a auto engine is gave by the burning of petrol.

Only 30% of the energy is transferred to advantageous output power as movement.

About 70% of the energy is moved to the surroundings in the form of thermal power and sound. A few of the energy is shed in cooling dvery own the engine.

40% is lost as thermal to the surroundings.

20% is shed in cooling the engine.

10% is lost as sound.

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This is the labeled Sanvital diagram:

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In a power terminal, power is moved via the system in order to create power. Throughout the carry of power via the device, some of the energy is wasted.

Use the internet or other resources to discover the various ways in which energy is transferred to the surroundings as wasted energy in the time of the production of electricity in a power plant.

Write a short paragraph to define the power transfers. How is the input power transferred with the system and also wright here is the wasted energy lost?


The paragraph should include the following information:

Coal is burned and the power is moved to the water and also offered to boil the water. Some of the power is shed throughout this process. The heavy steam from the boiling water is offered to rotate the wind turbine. The kinetic energy of the steam is transferred to the turbine. Several of the energy is shed to the surroundings as sound and also thermal power. The kinetic power of the wind turbine is transferred to the generator. Some of the power is lost to the surroundings as sound and thermal power. The kinetic energy of the generator is provided to generate electrical energy.


Draw a Sanessential diagram for the energy transfers.


An example for a Sankey diagram for a power plant is provided listed below. You deserve to likewise watch what learners have uncovered out and then attract one on the board to show the transfers.

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Remember, power is measured in joules (J).


Energy entering a mechanism is called the input power. The power is moved in a mechanism to carry out a helpful output power. Tools, appliances, vehicles and equipments all carry out useful energy outputs. Not every one of the input power is moved to a valuable output. Some of the power is wasted or shed. The advantageous output is therefore much less than the input energy as some of the output power is wasted. An example is a light bulb wbelow the input is electrical energy and also the useful output is light. However before, a big amount of the power is shed to the surroundings as thermal energy. The effectiveness of a device is determined by just how much of the input power is moved to valuable output power. The greater the wasted output power, the much less reliable the mechanism. A Sankey diagram is provided to present the power transfers in a mechanism. In a Sankey diagram, the arrows represent the percentage of the input energy which is transferred to valuable power output and the percent which is moved to the surroundings and wasted.

Concept map

Complete the principle map by providing 2 examples of units wright here power is moved to the surroundings and also "wasted" as sound and thermal energy, and one example of wbelow the wasted power output is light.

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Teacher"s variation. The examples given right here are not the just examples. Learners can usage any kind of of the examples debated in the chapter which are appropriate.

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Revision concerns
Draw a simple Sancrucial diagram to show the power transfers in a system wbelow the wasted energy output is more than the valuable energy output. <4 marks>

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In the chapter, learners offered percenteras to attract their Sankey diagrams. The complying with is an expansion and also starts off with a straightforward example which they have actually currently checked out in the chapter, namely a light bulb, yet the power transfers were stood for as percentperiods. In the first example below, we currently start off with 100 J instead of 100%. The Sancrucial diagram will certainly be straightforward to attract. However, in the succeeding examples, the input power is more than 100 J. Learners perform not should calculate the percentperiods, yet the thickness of the arrows must be representative of the amount moved.


For each of the complying with instances, attract a labelled Sanvital diagram to display the amount of input power, advantageous energy and wasted energy.

An electric torch converts 100 joules (J) of electrical power to 10 J of light power and also 90 J of thermal power. <3 marks>

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An electric torch.

A tv has actually an energy output of 500 J. 400 J is in the create of light. 50 J is in the create of sound and 50 J is thermal energy. <3 marks>

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A television set.


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a. The potential energy from the batteries in the torch is transferred to the filament of the bulb. The power is transferred to the surroundings as thermal power and also light. Many of the energy is moved as thermal energy which is not helpful and just some of the energy is transferred as light.

b. The energy from the TV is transferred to the surroundings as thermal energy, sound and light. The light and sound are valuable because they are the images and also sounds we want to hear. The heat is wasted energy.

c. The energy from the hair dryer is supplied to warmth the air and also dry our hair. Two thirds of the energy is helpful thermal power yet one third is transferred as sound, which is not advantageous to us.


An electric geyser transfers power to thermal power in the water pshort articles as the water is warmed up. The valuable output is the thermal energy to warm the water. However before, some of this thermal power deserve to escape from geyser to the surroundings. This is therefore wasted. In order to make the geyser system even more reliable so that the useful power output is higher and also the thermal energy loss is lessened, the geyser should have actually an insulating covering, to mitigate energy transfer to the surroundings by conduction.