What is Power output: Definition and 138 Discussions

In radio transmission, transmitter power output (TPO) is the actual amount of power (in watts) of radio frequency (RF) energy that a transmitter produces at its output.
This is not the amount of power that a radio station reports as its power, as in "we're 100,000 watts of rock 'n' roll", which is usually the effective radiated power (ERP). The TPO for VHF-/UHF-transmitters is normally more than the ERP, for LF-/MF-transmitters it has nearly the same value, while for VLF-transmitters it may be less.
The radio antenna's design "focuses" the signal toward the horizon, creating gain and increasing the ERP. There is also some loss (negative gain) from the feedline, which reduces some of the TPO to the antenna by both resistance and by radiating a small part of the signal.
The basic equation relating transmitter to effective power is:












{\displaystyle TPO\ \times \ loss_{feedline}\ \times \ gain_{antenna}\ =\ ERP}
Note that in this formula the Antenna Gain is expressed with reference to a tuned dipole (dBd)

View More On Wikipedia.org
  1. T

    A question regarding power generation in MHD method

    First, I want to put forward an imaginary scenario where an ionized flow is being used to generate power/electricity by MHD power generation method. The temperature of the ionized flow is the same as the surrounding atmosphere. Power/electricity is generated as the flow is ionized. Now, if the...
  2. A

    How is power limited from renewable sources

    I'm an engineering student and I recently watched a lecture from a wind farm control system engineer. He said that the national grid will call them up and ask for a specific amount of power. He then enters that value into the system and it will automatically adjust to achieve that power output...
  3. T

    Calculating Area of a Tesla Turbine | Power Output Formula

    Found this paper regarding performance of Tesla turbine. At the page 23, a formula regarding possible power output from a Tesla turbine is given. But, I want to know how to deduce the area given the formula. Tesla turbines are discs placed one after another with specific gaps in between the...
  4. D

    B Magnetic field and generator power output

    Hi, I am confused about whether decreasing the magnetic field used for a generator could increase the generator's power output. I used four equations: 1. Torque = Force x radius 2. Torque = NIAB (N = number of turns, I = current, A = area of armature, B = magnetic field). 3. emf =...
  5. SpinnerDude

    I Calculating power output on a spin bike

    So...I have a home spin bike which unfortunately lacks the sensors of some of the more expensive models. What I'm trying to do is work out if I can dynamically calculate my power output. The spin bike itself has: - An 18kg flywheel of radius 30cm - Direct drive between the crank and the...
  6. F

    How do atheletes sustain high power output, physiologically?

    I am ~180lbs and have been lifting weights for about 12 years straight. I have also been running 3-4 times per week for the last 8 ish years. I have recently gotten into cycling, and noticed at the gym on the Schwinn "spin" bike, I will have peaks of around 400-500 watts, but it's definitely...
  7. M

    How to calculate the electrical power output using the Organic Rankine Cycle?

    Basically this would be a closed loop geothermal system for electrical power generation. The system would consist of 2 Horizontal Wells connected creating a U-shaped closed loop cycle using thermosiphon effect, with constant recirculation. It's not really a conventional geothermal power...
  8. Mayan Fung

    How to get maximal power output from solar panels in reality

    I learned that solar panels have their maximal power output at a particular voltage and current level. If we want to get the max power, we have to connect a load with a specific resistance. However, in reality, how does the solar plants solve this problem? I guess they won't allow the power...
  9. K

    Climbing a ladder in an elevator

    I have found the apparent weight of the man in the accelerating elevator My question is about what speed I should use in the formula for the power output P = F ⋅ speed My common sense tells me that the speed I should us is the speed v the man is climbing the ladder , because if the...
  10. bbbl67

    I Power output of red dwarfs turning yellow and blue?

    Although the universe is not old enough to experience these yet, but near the end of the lives of red dwarf stars, they will go from red to yellow, to blue eventually. Does this result in additional heat being given off of the surface of those stars? And if so, then does the habitable zone of...
  11. R

    What is the electrical power output of a turbofan engine?

    Hello All, Happy New Year! A typical modern turbofan engine system creates lift as well as propulsion for the aircraft. Somewhere inside the system, the fast rotating device also works as a generator (alternator) to produce the electricity powering electrical/electronics equipments. What is the...
  12. J

    Power output from a falling masss over a time period

    How did you find PF?: youtube [Moderator: moved from new member intro forum]How did you find PF?: youtube i need a falling mass over time /joules per kilo over 1hr time also need to know how to figure gearing to maintain fall over time in regards to a set resistance such as a 5 kw alternator
  13. Fdtroya

    Which factors determine the power output of a permanent magnet alternator

    To be more precise the generator has to be able to produce around 1.5 Watts from a person spinning its axis, which is why I was thinking of putting a gearbox in my design but I need to know how much Torque would it take to spin the axis and at what rpm would the generator be effective.
  14. J

    Intensity of sound, power output

    I is proportionate to E. r = 4.3xxm So I put 0.75I The answer is 49mW.. But I got 97.xxmW What is wrong?
  15. Chandrakanth_balusa

    Estimation of the Power Output of a steam turbine

    Hoow can one estimate the amount of steam required to generate certain amount of electical power mathematicaly?
  16. T

    Power output of a theoretical generator

    so, assuming that you know all of the aspects of your theoretical generator, apart from the voltage and current, how would you work it out. I know that it is possible, but i can't find anything that I understand, or is even valid online. There should be some equations i can use to work it all...
  17. K

    What is the Power Output of Gravity?

    Homework Statement : It takes gravity 1.43 seconds to pull a 3.67 kg cat down from a 10m tall ledge. What is the power output of gravity? [/B] Homework Equations P=mgd/t P=w/t P=power M=mass G=gravity D=distance W=work T=time[/B] The Attempt at a Solution P=(3.67)(9.81)(10)/1.43 P=251.77
  18. M

    Calculate Avg Power Output for 75kg Person Walking 100ft in 3min

    Homework Statement Calculate average power output for a 75 kilogram person walking from ground level up stairs to a final height of 100 feet (then stops) in a time of 3 minutes Homework Equations P= work/ time or P=Fv The Attempt at a Solution I thought this was more of an energy problem...
  19. A

    Power output of a intercooler and turbocharger

    Homework Statement The power output of an automobile engine is directly proportional to the mass of air that can be forced into the volume of the engine’s cylinders to react chemically with gasoline. Many cars (like a 2008 Mini Cooper S) have a turbocharger, which compresses the air before it...
  20. M

    Automotive Max Power Output with Air-Fuel Ratio

    How can the slightly richer Air fuel ratio produce higher power while the temperature it produces is lesser than slightly leaner(slightly leaner than stoichiometric for best economy)? FYI:I understood that ,at the stoichiometric ratio(precisely slightly leaner due to fast operation of engine)...
  21. A

    Calculating the power output from a persons mouth

    Homework Statement Speech at a distance of 45.1 cm has a sound level of 59.3 dB. Assuming that the energy in the sound spreads out equally in all directions from the person's mouth, calculate the total power output from the person. Given: Distance= 0.451m Sound level 59.3 dB P=? J Homework...
  22. A

    I Photon emission, power output (and black holes)

    I recently re-read an article by Muller (https://arxiv.org/pdf/1606.07975.pdf) about the flow of time, and the possibility of time reversal given sufficient energy dissipation (basically during black hole evaporation, he concludes). Although the paper is on arXiv and not peer reviewed, Muller...
  23. Y

    Fire Hose Power Output, Given Height and Radius of Hose

    Homework Statement A fire hose for use in urban areas must be able to shoot a stream of water to a maximum height of 34 m. The water leaves the hose at ground level in a circular stream 4.0 cm in diameter. What minimum power is required to create such a stream of water? Every cubic meter of...
  24. T

    Measuring the Power Output of a Generator

    Hey folks, I built a generator for fun and I would like to find out how much power it is producing when I use it. I have a way of measuring mechanical power in but I am not quite sure on how to measure electrical power out. I'm thinking I could use some LEDs to create a load (or maybe...
  25. E

    Calculating Solar Panel Area Needed for a 1MW Power Output

    Homework Statement Hello everyone, I'm working on a (simplified) Mars energy model in which I need to calculate the area of land I need to cover in solar panels in order to achieve an particular power output. Say the land I'm looking at receives a constant solar irradiance of 100W/m^2 from...
  26. C

    Increasing the Power Output of a Turbine

    I have a hydro turbine spinning at 62.746RPM and it produces 170.195Nm of torque. It generates 1.1183kW but ideally, I would like to step it up to at least 4.5kW. Is this possible using a gearbox and if so how can it be done?
  27. P

    Low DC amp through small circuit of 14 AWG copper wire?

    I have a 2 AMP regulated DC power supply, with variable voltage 3 - 12 v. If in a small circuit, i.e, small copper wire with 1 ohm resistor. Why am i not getting at max Amps?
  28. C

    Power Output of a Turbine (Rotational Energy)

    Homework Statement A Verdant Power water turbine (a “windmill” in water) turns in the East River near New York City. Its propeller is 2.5 m in radius and spins at 32 rpm when in water that is moving at 2.0 m/s. The rotational inertia of the propeller is approximately 3.0 kg∙m^2. Determine...
  29. C

    Determining power output at different time intervals

    Homework Statement A 49.0 kg sprinter, starting from rest, runs 58.0 m in 9.90 s at constant acceleration. What is the sprinter's power output at 1.90 s , 3.00 s , and 5.70 s ? Homework Equations ##d=v_it + \frac{1}{2}at^2## ##F=ma## ##W=Fd## ##P=\frac{W}{t}## The Attempt at a Solution I got...
  30. E

    Struggling with light calculations (incident power output)

    Hi guys, not sure if this is the right place. Its to do with an electronic project I've been working on. However please point me somewhere else if you know anywhere better suited! (It is quite a long post sorry) Basically, I have created an LED array used for stimulating cells with light and I...
  31. J

    Power Output Given Certain Torque

    Hi, I have a problem that I've been trying to figure out for a while but cannot seem to get on my own. I'm trying to figure out how much power will be generated in a motor given a certain amount of torque. The problem is, to find the amount of power output , I also need to know the rotational...
  32. alexandria

    Solving Physics Homework: Power Output of Heater

    Homework Statement Homework Equations relevant equations listed with each question The Attempt at a Solution a) to solve for the power output of the heater, i used the following equation: Power = Energy/time i already know that Energy = Quantity so based on this, i can solve for Q = mass(ice)...
  33. J

    Power Output of Radiation from a Solenoid with Linearly Decreasing Current

    Homework Statement A solenoid contains 610 cycles, with a radius of 0.136m and a length of 0.87m. The current of the solenoid decreases linearly from the maximum value I0 to zero through the equation I(t)=I0−bt, where I0=0.31 A and b=0.21 A/s. What is the power output of the electromagnetic...
  34. S

    How do I calculate the magnitude of initial acceleration?

    Homework Statement A system consists of a bicycle and a cyclist traveling at a constant velocity along a horizontal road. The total resistive force acting on the system in 4.0N and its speed is 8.0 m/s. Calculate the useful power output of the cyclist. The cyclist stops pedalling and the...
  35. amrmohammed

    Self-regulating heating cables low power output

    Hello, Why do self regulating heating cables have such low power output per foot? Power output in these cables does not exceed 20 W/ft at 10 degree C, and decreases as the temperature goes up. Many of the cables I saw can withstand high temperatures (250 degree C power off and 150 degree C...
  36. P

    How to Calculate Power Output for Lifting and Flinging Objects?

    1. Homework Statement Homework Equations P=dW/dt The Attempt at a Solution I feel like I did something incorrect because I didn't use the vertical distance at all. If I'm wrong, does it have something to do with the displacement?[/B]
  37. A

    Calculating Pump Power and Fountain Height from Water Ejection Speed

    Homework Statement A pump draws 500 kg of water/min from a 12 m deep well. The water is ejected with a speed of 20 m/s. a) What is the power output of the pump? b) How high is the fountain (ignoring air resistance) Homework Equations The Attempt at a Solution For part a I found the potential...
  38. amrmohammed

    Why Mineral Insulated Heating Cables have power output limit?

    Hello Why does Mineral Insulated heating cables have such limited power output per feet and maximum operating voltages? I thought it has to do with the dielectric strength of the MgO, that is used as an insulation in the coaxial cable, but the dielectric strength for MgO is higher than the...
  39. S

    Power output of automobile at different engine rpm

    I figure my 2.4 liter Volvo will burn about a liter of gasoline over an hour of idling (source: Natural Resources Canada). Since a liter of gasoline contains roughly 33.8 million joules (~9.4 kilowatt-hours) of energy, I figure that that means my car idles at a power output of around 9.4...
  40. R

    Relating Power output of a sound wave to the pressure....

    ... it's amplitude exerts. During cavitation a sound wave is applied to a liquid and breaks it apart and gas pockets are formed. The frequency and the amplitude of the sound wave effect the bubble/s. My question is, if I have the power output of the device then how would this relate to the...
  41. M

    Check my answer for power output question

    Homework Statement a 0.25 kg piece of ice at -30°C is warmed by an electric heater and the following graph of temperature is produced. -use the information on the graph to determine the power output of the heater the graph shows that the ice went from -30degC to -10 degC in 150s Homework...
  42. JamesB93

    Dynamics assignment, power output of car

    I'm currently studying Mechanical Engineering at Level 3 in the UK and I'm beginning my integrated masters in September. I've missed a large chunk of my studies this year due to a broken collarbone I sustained earlier in the year. Instead of getting any special dispensation I'm trying to work my...
  43. A

    Calculating Power Output of an Automobile Engine

    Homework Statement During the power stroke in a four-stroke automobile engine, the piston is forced down as the mixture of combustion products and air undergoes an adiabatic expansion. Assume (1) the engine is running at 3400 cycles/min; (2) the gauge pressure immediately before the expansion...
  44. F

    Calculating Total Power Output of a Speaker at a Given Distance

    Homework Statement A speaker emits sound waves in all directions, and at a distance of 28 m from it the intensity level is 73 db. What is the total power put out by the speaker, in watts? ( reference intensity I_{0} is 1.0 × 10-12 W/m2.) Homework Equations P= I*A I = I_{0}*10^{B/10} SA =...
  45. H

    Measuring power output by modified prony brake

    Hi guys I have problem, basically I want to measure the power output from a water wheel. so basically I measured the power output by connecting the pulley that attach on the shaft of the water wheel. then this pulley is connected to other pulley which sit on the shaft of the DC motor. this DC...
  46. J

    Power output by basketball player when jumping

    Homework Statement A ##\small{105\!-\!kg}## basketball player crouches down ##\small{0.400\ m}## while waiting to jump. After exerting a force on the floor through this ##\small{0.400\ m}##, his feet leave the floor and his center of gravity rises ##\small{0.950\ m}## above its normal standing...
  47. A

    What is the Average Power Output of a Human Heart Pump?

    Homework Statement during a human heart beat, 20g of blood are pushed into the main arteries. This blood is accelerated from a speed of 0.20ms-1 to 0.34ms-1. For a heart pulsing at 70 beats per minute, calculate the average power of the heart pump. Homework Equations KE=1/2mv2 The Attempt at a...
  48. L

    Power output of an anchored propeller

    I have a motore with a propeller anchored to a load cell to measure the lift produced at varying power inputs. This is for a student activity I am running and I wanted to show that though more power in gives more lift there is a point after which efficiencey starts to go down again so I tried to...
  49. M

    Power output of a hydroelectric plant

    Homework Statement In a hydroelectric plant, water falls from a high elevation to a lower elevation,losing PE in the process/ In doing so, it turns turbines which generate electricity. In a particular hydroelectric plant, water flows at a rate of 400 kg/s. If 80% of the PE that the water...
  50. G

    Controlling the power output of a power resistor

    Homework Statement Hi, I am working on a temperature control system which involves using a power resistor to heat a block of aluminium and a thermocouple to measure the temperature. Both the thermocouple and the power resistor will be controlled using the NI USB-6008 and Labview. As my...