# What is Wattage: Definition and 67 Discussions

Electric power is the rate, per unit time, at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second.
Electric power is usually produced by electric generators, but can also be supplied by sources such as electric batteries. It is usually supplied to businesses and homes (as domestic mains electricity) by the electric power industry through an electric power grid.
Electric power can be delivered over long distances by transmission lines and used for applications such as motion, light or heat with high efficiency.

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1. ### I Minimum light bulb wattage for solar simulator

I am trying to design a simple homemade PV solar simulator. I have picked metal-halide lamps as my light source. If the PV panel has an area of 1m^2 and I wanted to achieve spatial uniformity across the irradiated surface with an irradiance of 1000 W/m^2, how do I go about selecting what...
2. ### What continuous wattage can I get out of a 12v lantern battery?

I have a C-Pap machine, and I'd like to put together something to power it for a few hours if we have a blackout. Wiring two of the above lantern batteries together should produce 24 volts. But I can't find any info on how much wattage you can draw from these before the voltage will sag. It...
3. ### What factors determine wattage of electrons flowing through a wire?

Preface: I am new to physics and am trying to learn on my own, though I hope to take a class soon. I looked for a forum for beginners but didn't see one, but this seemed to be the closest forum. So I hope I can get some help with my question here. If it is the wrong forum, feel free to...
4. ### Build Astable 555 Timer 8-Bit Computer Clock with Ben Eater's Project

Am trying to build an Astable 555 timer 8 bit computer clock. Ben Eater's project. Resistors are specified, but with no reference to wattage. Does anyone know the appropriate wattage for the carbon film resistors please?
5. ### Automotive How can I accurately determine the necessary wattage for a motor in my vehicle?

Hi fellas, Really how to select the wattage of the motor as I'm stuck with that. I came across several formulae, yet still unable to do it so. Vehicle Mass = 120Kg Load Mass = 100Kg (max) Front tyre = 8" x 2 Back Tyre = 12" x 2 Tyre material = Polyurethane Dimension = 25" x 35" Speed = 9.3km/hr...
6. ### Wattage an of engine sufficient to move a car

I am tutoring a student, and this question was given to her. I believe it is not clearly stated and wanted your opinion. I hope this is the best forum for this. 1. Homework Statement What is the minimum wattage required to accelerate a car of mass m (don't remember the value) from 0 to 28 m/s...
7. ### Power relation to lightbulb wattage

Power is measured in watts and lightbulbs are rated in watts. P = W/t and W = Fd What is being displaced? electrical current?
8. ### Tubular cartridge heater wattage

Hi, I have a machine equipped with 2000mm long tubular cartridge heater (230V, 1600W, 4mm diameter). This tubular heater is sandwiched between the two steel plates (2000mm long) i.e. the heater keeps the steel components hot. My problem is that the temperature of the steel components varies...
9. ### Sizing a Solar Array To Boil Water

Hello, I am having a hard time deciding the size of a solar array to boil water for a school project. Before putting any thought into the subject I simply thought that I would just take the wattage of the panels and add them up since they are added in both series or parallel and then select an...
10. ### Electric Element Voltage Specifications?

Hello, I have a question about electric elements and their corresponding voltages. I am looking at powering a 1500W 120VAC element out of an ordinary kettle with a DC voltage supplied by solar panels. So, from what I understand, 120VAC represents the RMS voltage meaning that it would require...
11. ### What really is "energy" -- is it the amps or the wattage?

If volts is only an "electro motive force", that is, it only pushes, and resistance is what tries to hold everything back, and "amperage", that is, current, is the actual electricity ( or not, that is my question ) and watts is the calculation of everything together and the total output, is it...
12. ### Keep setting fire to discharge load resistor - Wattage limit

We kept getting some voltage spikes back into our amplifier. One of the things we put in place is a 10kOhm resistor (discharge load) connected to the output of the amplifier. However, the resistor keeps burning and setting on fire. The amp company offered a way on checking this... I'm really...
13. ### How to calculate the wattage needed

I have a project in which a client is wanting an outside glass deck floor to be heated to keep from freezing. Below the floor is ambient temperatures. The glass is 1.25 ( 3 layers of 3/8" with a /060 inter-layer between each lite of glass) thick each panel is 30" x 60". I don't want to...
14. ### What is the effect on audio of using larger wattage resistor

Hi, In general 1/2 watt resistors is what I see in tube guitar amps. I built one with 1 watt resistors and can not hear any difference. I assume shot noise will decrease with larger wattage values. Other than heat dissipation, how is a 1 watt resistor different from a 1/2 watt resistor...
15. ### Is it possible to estimate a light source wattage remotely?

I'd like to know if it's possible to roughly estimate a light source wattage remotely, knowing the distance and perhaps estimating that at such a distance it's still above the minimum human recognizable threshold at night (in a light polluted area). Maybe using a DSLR camera could help by...
16. ### Wattage in a MWO (microwave oven)

What is the main determining factor in determing the watts in a MWO? I'm not asking how it is measured I understand how to do that, I'm asking what the engineer uses to determine it. Is the output voltage of the transformer more responsible than anything else? It seems they all put out the same...
17. ### Calculating Wattage with Sine Wave

So my question is about calculating wattage with a sine wave. So with speakers I always just thought of it as the basic vi=w So a sine wave of 12v through 4 ohms will produce three amps and thus 36watts. But when you put a square wave and use pulse width modulation on something like an led or...
18. ### Electrolysis Wattage: A New Engine Concept Explored

After my endeavors on Electro-Tech-Online, I have concluded that they are the least bit constructive. Now, I wasn't sure which section to post this in, so I went with EE. I'm currently developing a new engine concept similar to a Stirling Engine, and I have no idea whether it will actually...
19. ### Questions about Charging Speeds and Wattage

Hi, I'm not sure if this is a correct place to ask this, but i have a question about the charging speed for the usb chargers for phones and tablets. from what I have gathered, the device being charged is the one that pulls the current from the charger, so if a 1 amp input device is charged with...
20. ### What Wattage Rating Is Needed for a 33Ohm Resistor in a 9V, 1A Circuit?

Hello, I am new to any type of engineering and just have been working with Arduinos and other microcontroller lately for fun. I am creating a prototype for a project that requires me to use a 9V power supply with 1Amp to power the Arduino(note, the arduino only needs around 300mA to run). I...
21. ### What is the minimum wattage rating the resistor should have?

Homework Statement [/B] The question "What is the minimum wattage rating the resistor should have?" comes after a previous problem I did to determine the maximum and minimum current when given a resistors tolerance. Here are all the values from that problem, some aren't really important but...
22. ### Effect of Voltage Increase on Battery Wattage

If we boost voltage from 3.7v to 12v, is this will affect on watt we consumption from the battery or make your battery discharge faster?
23. ### Calculating a simple generator's output power (wattage)

Hi All, I am thinking about building a simple electrical generator (to use wave power), and I am trying to make sure I clearly understand the theory and expected results before starting the project. I have two basic questions: 1) How do I calculate the generators maximum current and...
24. ### Calculating actual power (wattage) created by a simple generator

Hi All, I am thinking about building a simple electrical generator, and I am trying to make sure I clearly understand the theory and expected results before starting the project. I have two basic questions: 1) How do I calculate the generators maximum current and wattage, if i know the...
25. ### What is the Wattage Calculation for a DIY Generator with Multiple Coils?

Hello, I'm building a generator and have completed initial phase. I made coil with 300 turns, which gives me 12v when rotor is turned at 2000rpm, if I short the coil it gives me 16 amp. 1] Now I'm wondering what is the output wattage of the generator I built / described? 2] If I use 18...
26. ### Getting correct wattage from lead-acid battery

Hi, So I have a question that I feel is best suited for people who know much about electricity and circuits. I have a 12V 7Ah sealed lead-acid battery (here, FYI http://www.parts-express.com/pe/showdetl.cfm?Partnumber=140-366). I also have a small stereo amplifier, 12VDC 2A, that is...
27. ### Inertia and bicycle wheels related to wattage and time

In the bicycle industry, there is a lot of marketing saying that rotational weight is more important than static weight when it comes to accelerations and competition. I understand I=mr^2 but how do you compare differences. Keeping the the hub/spokes constant, how much advantage would you get...
28. M

### Can a device use more wattage than it's rated for?

We're talking about high-wattage things like boilers, radiators, etc., things that use something like 500-1500W an hour, but aren't as advanced as computer hardware (where you can tune everything in the BIOS). Can such equipment, even though it's rated for say 800W, consume more (810, 850, 900...
29. ### Rated Wattage vs actual wattage

I have an electric heater which is rated 2000W, 230V . Is it that the OUTPUT (thermal energy/coming out as hot air) is capable of transfering 2000J of energy to the surrounding room per second ? OR The heater needs a 2000J of electrical energy per second to power it (at max) so that it...
30. ### Seniority of Wattage vs. Amperage

Was wondering if I kept the wattage for say a 100 watt bulb constant but varied the voltage would the light be able to continue functioning normally? Also, assuming this is true does this hold for more complicated circuitry? Thanks.
31. ### Calculating Wattage Rating in Series/Parallel Circuits

Homework Statement When calculating wattage rating, if you have resistors in both a series and in parallel circuits can you still use P = V2/R to solve for the wattage rating over each resistor if you're given the voltage of the battery or do you have to calculate the voltage drop after each...
32. ### Solar Panel Wattage: Altitude Effects Explored

At what altitude does a solar panel see a noticeable increase in wattage/cubic meter if it is lifted into the air? I understand the maximum is a bit over 1 kilowatt/meter2 at sea level (not actually converted to usable energy, this is much less and depends on the technology) but that this...
33. ### Help in designing water turbine for given wattage

We need to design an archimedes screw turbines to power a pump of 80 watts. Any tips to design this? I have tried a way, but I think it's very wrong. Thanks in advance :)
34. ### Understanding Wattage of a Blender

If a blender has a power of 800 watts, what does that mean? Doesn't the power output depend on the torque or speed of the motor, which depends on what you're blending? A motor that is spinning freely should have no power output (assume superconducting wires), because there is no torque in...
35. ### Wattage requirement for step-up transformer

Hello,I want to investigate the feasibility of buying a step-up transformer(110/120v to 220/240v)in order to plug in a 20 amp 240v portable electric heater that is rated at 4000 watts.The 110/120 comes from a standard wall outlet in a home built in 1995.I want a portable heater set-up that is...
36. ### What is the Relationship Between Intensity and Wattage?

Homework Statement OK, so this is a very basic question but i am uncertain what the relationship is. I know its logarithmic, but i don't know how to draw a conclusion. Here is the question: If you want an amplifier which will give a sound output which is twice as lod as your present 20 W...
37. ### Wattage delivered using triple integral help

Useful equation. Avg. Power p(t)=(V^2(t))/R My attempt at instantaneous power was p(t,V,R)= ∫(0->1 for t ∫0->5 for V and ∫0->.1 for R V^2(t)/RdvdRdt Integrating I go the triple integral of V^3t^2/6R^2 Substituting my values in gave a wattage of 1,250 watts/m^2 at t=1 second, v=5...
38. ### Importance of Wattage Difference

Hello, me again with another rookie question. lol I've almost completed all of the circuits for my robot; however, I noticed that the parts list required all of my resistors to be 1/4 watts, but the majority of resistors I've applied are 1/2 watts. I'm kind of pressed for time right now so...
39. ### Can cell phone radiation cause harm?

Hi Experts, there are a few types of gsm frequencies eg. 900/1800/1900/2100 MHz. Is it true that the higher the frequency the more watts consumed? regards Ramone
40. ### Determination of VO2 from conconi test, wattage and max aerobic power?

Determination of VO2, lactate, max HR from wattage and max aerobic power? I'm interested in determining VO2 non-invasively. I came across this procedure. Will it work? Do you notice any flaws in the logic? : From: BlueIcarus...
41. ### Simple Wattage & Resistance Question Regarding Heat

Hello, I'm looking to make handlebar grip heaters for my motorcycle, and so I read a few things online regarding the basics. The most important thing i need to figure out is just how much resistance i need from my wires for the right temperature. Ohms Law states V = I x R and Wattage = V...
42. ### Maximum wattage for American power outlets

Is there a maximum power that can be drawn from electrical outlets in America? Also, I was curious if this maximum power is exceeded, would it limit the charging of other devices in the same house but connected to other outlets.
43. ### How Does the Sun's Power Output Compare to a Car Battery?

Homework Statement A) How many W does 1 kg of the sun’s interior produce via nuclear reactions, on average? Compare the sun with a carbattery, which typically produces 190 W/kg. Which body wins? B) Estimating the time the two objects are providing their respective power, compare the energy in...
44. ### Calculating Wattage Rating for Generator to Power Electric Motor

What would be the wattage ratting for a gas/diesel generator to power an electric motor with these specs. 72-144VDC 190A Continuous 43.7HP Continuous Thanks
45. ### Resistor Wattage: Find Out If You Need Bigger Resistor

I have a circuit that uses a resistor to drop the input voltage. From my calculation, the power dissipation thru the resistor is less than it's wattage rating but yet the resistor is hot to the touch. Should I use a bigger resistor because it's too hot to the touch or should I keep using it...
46. ### Determine the Minimum Wattage Rating for Resistors

Minimum wattage rating ?? Homework Statement Hi everyone ,, got the following question a. Find the total resistance, current and unknown voltage drops b. Verify KVL around closed loop c. Find the power dissipated by each resistor and note whether the power delivered is equal to the...
47. ### What is the difference between voltage drop and wattage?

Voltage drop is how much energy a device uses. Wattage is the rate of energy transferred into the device per unit of time. Aren't both essentially the same thing? Or am I just confused?
48. ### Ohms and wattage of resistor

I am trying to determine ohms and wattage of R2 on attached schematic. The resistor fried so I can't tell anything about it This circuit is a recharger for a cordless black and decker drill Thanks
49. ### Which Wattage Resistor is Best for a Noiseless Filter Design?

In a filter where 1/4 watt resistors is enough would the filter be less noisy if I use 1/2 watt or more or should I use the least wattage resistors needed?
50. ### Relationship between Cadella and Wattage?

Is there a general relationship that can be used for LED lights tying togethor Cadella output and Wattage required?