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Examples of power

Examples of power are limited only by the imagination, because there are as many types as there are forms of work and energy. (See [link] for some examples.) Sunlight reaching Earth’s surface carries a maximum power of about 1.3 kilowatts per square meter ( kW/m 2 ) . size 12{ \( "kW/m" rSup { size 8{2} } \) "." } {} A tiny fraction of this is retained by Earth over the long term. Our consumption rate of fossil fuels is far greater than the rate at which they are stored, so it is inevitable that they will be depleted. Power implies that energy is transferred, perhaps changing form. It is never possible to change one form completely into another without losing some of it as thermal energy. For example, a 60-W incandescent bulb converts only 5 W of electrical power to light, with 55 W dissipating into thermal energy. Furthermore, the typical electric power plant converts only 35 to 40% of its fuel into electricity. The remainder becomes a huge amount of thermal energy that must be dispersed as heat transfer, as rapidly as it is created. A coal-fired power plant may produce 1000 megawatts; 1 megawatt (MW) is 10 6 W size 12{"10" rSup { size 8{6} } " W"} {} of electric power. But the power plant consumes chemical energy at a rate of about 2500 MW, creating heat transfer to the surroundings at a rate of 1500 MW. (See [link] .)

A distant view of a coal-fired power plant with clearly visible cooling towers generating electric power and emitting a large amount of gases.
Tremendous amounts of electric power are generated by coal-fired power plants such as this one in China, but an even larger amount of power goes into heat transfer to the surroundings. The large cooling towers here are needed to transfer heat as rapidly as it is produced. The transfer of heat is not unique to coal plants but is an unavoidable consequence of generating electric power from any fuel—nuclear, coal, oil, natural gas, or the like. (credit: Kleinolive, Wikimedia Commons)
Power output or consumption
Object or Phenomenon Power in Watts
Supernova (at peak) 5 × 10 37 size 12{5 times "10" rSup { size 8{"37"} } } {}
Milky Way galaxy 10 37 size 12{"10" rSup { size 8{"37"} } } {}
Crab Nebula pulsar 10 28 size 12{"10" rSup { size 8{"28"} } } {}
The Sun 4 × 10 26 size 12{4 times "10" rSup { size 8{"26"} } } {}
Volcanic eruption (maximum) 4 × 10 15 size 12{4 times "10" rSup { size 8{"15"} } } {}
Lightning bolt 2 × 10 12 size 12{2 times "10" rSup { size 8{"12"} } } {}
Nuclear power plant (total electric and heat transfer) 3 × 10 9 size 12{3 times "10" rSup { size 8{9} } } {}
Aircraft carrier (total useful and heat transfer) 10 8 size 12{"10" rSup { size 8{8} } } {}
Dragster (total useful and heat transfer) 2 × 10 6 size 12{2 times "10" rSup { size 8{6} } } {}
Car (total useful and heat transfer) 8 × 10 4 size 12{8 times "10" rSup { size 8{4} } } {}
Football player (total useful and heat transfer) 5 × 10 3 size 12{5 times "10" rSup { size 8{3} } } {}
Clothes dryer 4 × 10 3 size 12{4 times "10" rSup { size 8{3} } } {}
Person at rest (all heat transfer) 100 size 12{"100"} {}
Typical incandescent light bulb (total useful and heat transfer) 60 size 12{"60"} {}
Heart, person at rest (total useful and heat transfer) 8 size 12{8} {}
Electric clock 3 size 12{3} {}
Pocket calculator 10 3 size 12{"10" rSup { size 8{-3} } } {}

Power and energy consumption

We usually have to pay for the energy we use. It is interesting and easy to estimate the cost of energy for an electrical appliance if its power consumption rate and time used are known. The higher the power consumption rate and the longer the appliance is used, the greater the cost of that appliance. The power consumption rate is P = W / t = E / t size 12{P= {W} slash {t} = {E} slash {t} } {} , where E size 12{E} {} is the energy supplied by the electricity company. So the energy consumed over a time t size 12{t} {} is

E = Pt. size 12{E= ital "Pt"} {}

Electricity bills state the energy used in units of kilowatt-hours ( kW h ) , size 12{ \( "kW" cdot h \) ,} {} which is the product of power in kilowatts and time in hours. This unit is convenient because electrical power consumption at the kilowatt level for hours at a time is typical.

Questions & Answers

what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
how can I make nanorobot?
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
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Source:  OpenStax, Unit 5 - work and energy. OpenStax CNX. Jan 02, 2016 Download for free at https://legacy.cnx.org/content/col11946/1.1
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