Efficiency Definition and 948 Threads

Efficiency is the (often measurable) ability to avoid wasting materials, energy, efforts, money, and time in doing something or in producing a desired result. In a more general sense, it is the ability to do things well, successfully, and without waste. "Efficiency is thus not a goal in itself. It is not something we want for its own sake, but rather because it helps us attain more of the things we value". In more mathematical or scientific terms, signifies the level of performance that uses the least amount of inputs to achieve the highest amount of output. It often specifically comprises the capability of a specific application of effort to produce a specific outcome with a minimum amount or quantity of waste, expense, or unnecessary effort. Efficiency refers to very different inputs and outputs in different fields and industries.

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  1. R

    Studying How Can I Extend My Study Hours Beyond Four Per Day?

    The subject of self-studying has been discussed extensively. However, one part that I find missing is an efficient workflow. I have 24 hours a day but I can only manage to study 4 hours a day (i.e., reading, understanding, taking notes, and doing problems). I have done this for months but I...
  2. DaveC426913

    B Graphing trip efficiency - distance over time

    I make this 60km trip every week or two and I've always been obsessed with tracking distance. time and velocity on trips. [ digression ] This is a graph I drew up of a different trip, years ago: This was long before Waze and Google Maps. I had a scrap of paper on my steering wheel and wrote...
  3. D

    B Using Interference Principles to Increase the Efficiency of Solar Panels

    The use of interference principles in quantum mechanics to convert solar energy into electrical energy can be represented through the concept of quantum dots, or nanoparticles, which have properties that contribute to enhancing the absorption of light and generating the photoelectric effect...
  4. bhobba

    New High Efficiency Power Lines

    I read an interesting article on progress in making transmission lines more efficient: https://reneweconomy.com.au/super-cheap-transmission-upgrades-could-double-capacity-and-open-floodgates-for-renewables/ While, of course, we do not discuss politics here, this new technology has many...
  5. rossc12

    Design

    I’m looking at designing a portable propane electric generator that’s light for camping ect’ What ideas on how to improve the efficiency on the alternator and the inverter from dc to could I improve upon or incorporate? Thanks Rosd
  6. Deathz

    Measuring Power output of DC generator

    Hello everyone, I would like to ask some questions regarding my thesis. I have a problem identifying which load I should use to calculate the power output of the small generator. I use an Archimedes screw turbine as the prime mover of my generator, and the water flow is low in my locality...
  7. F

    I Nuclear power plant vs coal power plant efficiency

    Hello, I have been reading that a coal power plant and a nuclear power plant have similar efficiencies, i.e. ~30%. This 30% refers to the conversion of thermal energy into electricity. For example, for 100 Joule of thermal energy, we only get 30 Joule out of electrical energy. How is that...
  8. R

    Can you help me understand this modification to a formula?

    Hello guys, I did a efficiency analysis with two different propellers. For that I build up an experiment to make measurements. The experiment is build up like this: You can see a prop inside the tube which after turning on will pump water from one side to the other. After a certain duration...
  9. SCHROEDERFPM

    Beginner circuits / ↓ the voltage & ↑ the efficiency

    So far this is what I have: I have the power source, two triple in a battery case, negative to the T emitter, T output to the (-) of motor, T base through a resistor to the switch, switch to the (+) of motor. I tried wiring the Led to this junction and the switch, but either the motor or the...
  10. P

    Estimating efficiency of a system

    Please see the attempt sketch. Basically I have four very inefficient DC motors all commonly turning a single drive shaft at the center of the system. Currently these motors that are 2.47% efficient individually able to produce 5 newton meters of torque at 28 RPMs. So my question is this. If I...
  11. P

    Automotive Total machine system efficiency

    Please see the attached sketch. Basically I have a system of three gear boxes, each with their own respective efficiencies. I'm trying to determine, at the end of this string of gearboxes, what the overall efficiency is. How might one go about determining this? Do you just take the average? 70 +...
  12. btostes

    A Does anyone know typical values of cutoff ratio in diesel engines?

    Hello, Does anyone know typical values of cutoff ratio in diesel engines? And how have they evolved through time? Thank you!
  13. S

    B Thermal physics, COP upper bound for heat driven heat pumps

    I made a presentation where I derived, or at least attempted to derive, the formulae for the upper bounds of the efficiency/cop (cop = coefficient of performance) for a heat engine, work driven heat pump, and a heat driven heat pump with 3 thermal reservoirs, hot, warm, and cold. There are many...
  14. singularcell

    Efficiency and Temperature in Heat Engine Cycles: Approaching Parts B, C, and D

    I didn't have much trouble with part a but I'm struggling with b,c, and d. I considered the efficiency formula for a heat engine e = work done by engine/ qh but i am unsure of how to approach it. for part c) not sure how i can get to Tc without knowing Th for d) my gut is telling me 5/2 but i...
  15. Ahmedbadr132

    Power Efficiency of Linear Piezo Electric Motors

    Hi I want to know the power efficiency of linear piezo electric motors in percentile.
  16. RandiSS

    Finding efficiency of an engine (with attempt)

    This was my first attempt which was not right. But it was at least a percent unlike my 2nd attempt. This was my second which I found on another forum website. It said it found the work of step 1, heat absorbed of step 2, work of step 3, and absorbed heat of step 4. However, the answers to the...
  17. M

    Long distance electrical transmission efficiency

    TL;DR Summary: Just need help with verification of data submitte 1 of 94 Efficiency distance over 3000 km +, plus Temperature over that distance 1-inch amorphous magnetic core 0.05 microns graphene 0.10 microns metallic PZT Helical copper wire with 15 mm...
  18. S

    Power and Efficiency without mass?

    Really perplexed me as the answer provided does not solve for mass ... seemingly wants to use mass as a unit of height? Or perhaps I'm off base ... really just curious if this is even correct or possible? Thanks in advance
  19. D

    I Just for fun: treadmill air conditioner efficiency calculation

    What approximate portion of generated heat from being active on the treadmill, both the person on it as well as the machines themselves would be compensated/cooled if the treadmill resistances would be disabled/removed and instead 1/2 end cylinders would be connected to an air conditioner...
  20. P

    B Calculating Fuel Efficiency of Rocket Going Near c

    How would you calculate the fuel efficiency of a rocket (around 10 tonnes) going near the speed of light?
  21. S

    Efficiency of a small electrical motor

    Hello All I've conducted an experiment to work out the efficiency of a small motor, and it comes out to be very low. Have I done my calculations correctly? I connected the motor to a gearbox (made from Meccano) and a winch and used it to lift a weight. I measured the DC voltage across the...
  22. W

    Open Gas Turbine - calculate T2, T3, T4, efficiency

    Hello, I am trying to solve a problem about an open Gas Turbine. The given information would be: - An open gas turbine draws in air from the surroundings having the m, cp, T1 and constant kL with the next values: , - The air flow is heat over natural gas supplied: - The pressure ratio is 𝜋...
  23. Poorneshwar 2

    I Difference between the thermal and mechanical efficiency

    Hello, I'm confused between the difference between the thermal and mechanical efficiency of a Sterling heat engines or heat engines in general. I hope you could be able to guide and help me. Thank you
  24. W

    Heat Engine Efficiency: How Ice Water Affects Performance

    Consider mixing ice water with the hot water and vice versa so that the two reservoirs are closer to the same temperature. What will happen to the mechanical/thermodynamic efficiency and ideal Carnot efficiency of a heat engine?
  25. D

    ROC Curve: Background Rejection vs. Signal Efficiency

    Hello forum, I am reading this article on quantum machine learning. At one point in the article (page 7) they plot the ROC curve as background rejection vs. signal efficiency. Researching these concepts (since I did not understand them fully), I read that ROC curves should be plotted as TPR...
  26. guyvsdcsniper

    Finding an expression for the efficiency of a heat engine

    My book states the answer to this problem is . I have gotten very close to the answer. My problem is my Tc/th and tc/tm are flipped compared to the solution. I feel like I am missing something in my algebra but can't see where I am going wrong. Could I get some help identifying where my...
  27. P

    I understanding a concept about motor efficiency

    I have tried to solve a problem about the amount of watts a motor needs to recive if i want an elevator of 1250Kg to move at a speed of 2m/s +/- 0,10m/s after 3 seconds. The motor has an efficiency of 0,80. I've tried looking at my teachers uni recording, but it doesn't seem to explain this part...
  28. B

    Why Are Solar Panels 21-22% efficient? How can efficiency improved?

    How efficient are solar panels? How can their efficiency improve? Besides their benefits, what are the ecological impacts of solar energy?
  29. tomcajot

    Energy Efficiency Tips for Homeowners

  30. B

    Net efficiency of a cascaded Carnot Engine and Fridge

    Here is a diagram of my interpretation of the problem: Where I'm thinking that the engine originally takes heat from ##T_h## to ##T_l##, in which case ## \frac { Q_{h} } { T_{h} } = \frac { Q_{l} } { T_{l} } ## and ## W_{out} = Q_{in} - Q_{out} = Q_h \left( 1 - \frac {T_l} {T_h} \right) ##...
  31. questionmonkey123

    Will this increase the Coefficient of performance of my refrigerator?

    If I orient my refrigerator such that the condenser coils at the back are facing a glass door (least insulation in room, cold outdoors) will CP increase? CP=Qc/(Qh-Qc) so Qh-Qc will be smaller thus CP larger. Could this damage refrigerator?
  32. T

    Which Is More Efficient: Dyson Fan vs Market Fans

    We all know about various kinds of market available blowers and their efficiency is well known more or less. I recently came to know about dyson fan/air multiplier I want to know which one, whether market available blowers or the Dyson fan is efficient in terms of creating mass flow rate at...
  33. gxa

    Finding Peak Values & Calculating Efficiency from Energy & Count Data

    At the end of the measurement I made with a detector, I only have the energy and count values as in the attached excel file. How can I find the peak values with the data I have and calculate the efficiency?
  34. kyphysics

    Can You Add Water to a High Efficiency Washer (There is So Little)?

    I used a HE (high efficiency) washer for the first time today at a relative's house (they're gone on vacation, so no one "warned" me). I washed a "medium" load of clothes ("medium" for a traditional/regular washer) and to my utter shock, the water level was only about 1/5 or 1/4 (at most) of...
  35. K

    I Theoretical maximum efficiency of a heat engine without Carnot

    Through an intriguing fictitious dialog between Sadi Carnot and Robert Sterling, Prof. Israel Urieli of the Ohio University shows that it is not required to invoke entropy, the second law of thermodynamics, and the Carnot cycle with the [ideal] adiabatic processes in order to find out the...
  36. G

    DC Motor Efficiency: Why Does Efficiency Plot Look Like Parabola?

    So I am doing an experiement about DC motors, and I would like to know why the efficiency plot looks like a parabola. What is the structure behind that. Thank you in advance
  37. Prinzmio

    Lowering the Golden Ratio: The Impact on Golden Section Search Efficiency

    Currently my task is to count number of iterations of golden section search verus interval bisection search of a function y = x^2. Golden section search took about twice the number of iterations than interval bisection search. If I lowered the golden ratio from 0.618 to 0.5562 , the number...
  38. V

    B Convince Covid-19 Vaccine Efficiency Through Statistics

    I have been trying to convince someone that it is wrong to compare the death percentages of two different populations (percentage of death of Covid-19 cases per category: vaccinated vs unvaccinated) in an uncontrolled setting (i.e. real-world data), and conclude that the Covid-19 vaccine does...
  39. A

    Inductor Efficiency via LC Oscillator

    I want to create an LC circuit with varying inductors and compare those inductors for efficiency. Would it be accurate to suggest measuring the area under the curve of the first cycle of the resonant frequency would determine which of the inductors are most efficient? If the area is greater...
  40. A

    B Question regarding Beta-voltaic cells and their efficiency

    Why are beta voltaic cells so inefficient? Is it because the incident electrons are incredibly fast? According to a research, the incident electrons that get absorbed by the voltaic material are so fast that most of their energy is wasted as phonon and sonic energy. If we substantially slow down...
  41. L

    Engineering Reviewing Efficiency of Otto & Diesel Cycle Heat Engines

    Hi, i have this question and don't understand it. can somebody explain what i have to do. i know a ideal engine is a engine running on carnot cycle i what the cycles are i don't know what relative efficiency is and what there looking for (Q) Review the relative efficiency of ideal heat engines...
  42. cheniour oussama

    Efficiency Analysis of a Voltage Multiplier Circuit

    hello, I did the simulation for the voltage multiplier in Vspace and I want to calculate the efficiency but the OUTPUT POWER is always negative. Do I need help? can I calculate the power losses of this sextupler voltage multiplier or it is very complicate to calculate it ?
  43. L

    Engineering Evaluate 2-stroke & 4-stroke Diesel engines therm & mechanical efficiency

    Evaluate 2-stroke & 4-stroke Diesel engines performance in terms of thermal & mechanical effiniecy HAs anybody got any links. all i can find is for petrol (2-stroke and 4-stroke). Is what i got so far any good?Thermal In a 2-stroke power stroke compared to a 4-stroke power stroke thermal...
  44. D

    Energy, work, power and efficiency when throwing a ball upward

    I don't have an idea of where to start. I tried to do Ein = 1/2 mv^2 ------ (1/2)(1)(10)^2 ----------- 50 but i don't know where to go from here
  45. D

    Work, Power, Energy, Efficiency

    The answer in the textbook says 0J but I am not sure what the concept behind it is. Does it have something to do with gravity?
  46. V

    Automotive The reason for the low efficiency of the ICE - zero shoulder crankshaft

    I don't know English well, translated using google translate. The working mixture ignites at TDC, and at this point the crankshaft looks up (0 degrees). As the piston descends, the force that the piston needs to travel a certain distance (for example, 1 mm) decreases, up to the moment when the...
  47. Dario56

    Enthelpy of Reaction and Efficiency of Galvanic Cells

    For electrochemical energy devices such as batteries or fuel cells working reversibly, efficiency is defined as: η=ΔrG⦵/ΔrH⦵ Since cell operates reversibly Gibbs energy change of the system is equal to electrical work done by the cell, so we can instead just use standard Gibbs energy of...
  48. yecko

    Engineering Can the efficiency of a solar cell with a single band gap reach 100%?

    I have tried looking up online with the photoelectric effect, it just mentioned the energy of the photon must have to equal to band-gap energy. Yet, it didn't mention if 100% can be reached in that case, or if a single bandgap makes any effect...
  49. Peter Jones

    The maximum efficiency of two continuous processes

    I think it reaches its maximum efficiency when it is two continuous Carnot process. Its efficiency then will be H= 1-(W1+W2)/(Q1+Q2), with W1/Q1>=T2/T1 and W2/Q2>=T3/T2 therefore H<= 1- (Q1.T2/T1+Q2.T3/T2)/(Q1+Q2), that is as far as i can go, have not got a result yet
  50. M

    Heat pump efficiency calculations - Compressor power issue

    The heat pump comprises of the 4 components: evaporator, compressor, condenser and expansion valve. Thermal power required to heat the building: 12.1 kW at condensing temperature tc = 44.3 deg C For the evaporator: vaporizing temperature tv = -7 deg C Subcooling temperature for the heat pump Δ...
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