The unit of measurement and SI unit for power, named after James Watt. It is equivalent to energy flow per second or Joules/Second. In electrical terms \$ W = IR = I^2 * R = V^2/R \$

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2answers
215 views

Will 0.16 amp rated fan replace a 0.3 amp fan?

I have a noisy PSU fan (400 watt Coolermaster PSU), It's 120mm and 12 volts. I have found an identical fan which is also 12v, but rated 0.16A, as opposed to the original 0.30A fan. I'm aware PSU ...
-3
votes
1answer
69 views

Is Ohm's law required to calculate Watts?

A buddy and I were having a conversation. One of us is convinced that Ohm's Law and Watts are the same thing. After much research I can not find anything directly pointing Ohm's Law to defining Watts, ...
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4answers
48 views

What is equivalent Resistor different Resistors put them in series or in parallel if they have a different wattage and different resistance?

What is equivalent Resistor of two this different Resistor put them in series or in parallel if they have a different wattage and different resistance? In practice somtimes we have a resistor with ...
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1answer
50 views

how long will an 11w bulb last on 3 x 500mAh 3.7v cells [closed]

I have this question that I can't seem to figure out. I have an 11 Watt bulb and 3 500mAh 3.7V Lithium Polymer Cells. And the question is how long the bulb will last. Can anyone help me with the ...
2
votes
4answers
560 views

Higher voltage or more amps?

Im planning on building a E-Bike and have made some calculations and only need my 190rpm/V brushless motor to spin around 600 rpm to give me a good speed. So by this calculation I only need to ...
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1answer
54 views

How much power does a wrist watch use to function? [closed]

I am wondering how some watches last for a year or more on battery. How many watts does a typical battery powered watch use to move the hands?
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1answer
72 views

How does one measure the power factor?

How does one measure the power factor? $$\text{power factor}\equiv\frac{\text{power}}{|V||I|}=\frac{R}{\sqrt{R^2+(1/\omega^2C^2)}}$$ for an RC circuit driven with \$V(t)=V_0\cos{(\omega t)}\$.
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2answers
47 views

Metal Halide Bulb with Instant On?

Is it possible to produce/obtain a metal halide (MH) bulb with the possibility to turn it off and on instantly - again and again? Most MH products require 30+ minutes to restrike.. Why is this? ...
2
votes
3answers
326 views

Ribbon Cable Wattage

What is the maximum wattage (and maximum recommended wattage) for a single ribbon cable wire. I believe the wire size is 28 AWG (maybe 26, but let's call it 28 to be safe), stranded copper. The ...
0
votes
1answer
36 views

Computing Power Requirement For Solar Setup

In relation to this question: Solar power wattage requirement I'm trying to get to the math of understanding my wattage for my plan solar-setup. I would like anyone here who knew can correct me on my ...
0
votes
1answer
79 views

How Much Heat will a 1800 Watt Bulb Produce?

I plan on placing a Metal Halide 1800 watt bulb 20 inches in front of me (not exactly in front but over my head) - will this produce more heat than I can handle? Someone said the question was vague ...
3
votes
3answers
111 views

Are \$\frac{1}{4}\$watt 4x\$\Omega\$ Resistor and \$\frac{1}{2}\$watt x\$\Omega\$ Resistor equivalent?

We know Ohm`s law: $$\Omega = \frac{V}{I}$$ $$W=\frac{A}{t} \space\space\space\space\space\space V = \frac{A}{q} \space\space\space\space\space\space I = \frac{q}{t} \space\space\space ...
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votes
3answers
147 views

How to turn a switch on/off repeatedly in 1 minute intervals?

I have a light bulb plugged into an outlet and I need to be able to turn it on and off again and again in 1 minute intervals for a period of 10 hours per day (a total of around 600 on/off events per ...
0
votes
1answer
46 views

Calculating Appliance Power Usage from Deep Cycle Battery

I want to figure out a formula for calculating appliance usage from a deep cycle battery and 120v power inverter. I own and operate a hot dog cart. I wish to add an electric grill/griddle to the cart ...
1
vote
1answer
129 views

How to Generate Light in the 10,000K Spectrum?

I need to generate a lot of light with the same spectrum as the sun - 10,000 Kelvin (10000K). I have searched around for hours, however all full spectrum lights available are either 5500K or 6500K - ...
1
vote
1answer
107 views

How to Convert 20,000 Lumens to Lux?

I need to generate 20,000 lux of light in an indoor environment. I am having trouble converting the lumens to lux using online converters ( I know there are many such converters but the questions they ...
1
vote
1answer
105 views

Chaining Multiple Bulb Socket Splitters Together?

I need to generate 20,000+ lux of light in a small indoor room. This is equivalent to around  30-50, 13 watt lightbulbs (each lightbulb is equivalent to 60 watt standard bulb) which produce around 800 ...
0
votes
7answers
241 views

Why are watts used as a measurement for some appliances?

Why do some appliances tout watts and some others advertise volts. I know watts is a measurement of volts*current but looking at just watts alone, what does that tell us about the appliance? Can't ...
0
votes
0answers
33 views

Exercise on a three-phase system where to evaluate the indication of the wattmeter

I have the following three-phase system where I have to evaluate the indication of the wattmeter W. Available data is: V = 380 ...
0
votes
2answers
75 views

I have virtually no understanding of how batteries work and charge, and have various questions on them

I'm doing research into portable power generators for a university class and need help understanding how charging a device works. From my research, I've found certain methods of harvesting energy can ...
0
votes
3answers
92 views

Obtaining a specific resistance

first of all, let me apologise for my inexperience with electronics. Now that's over with, I'm trying to follow a guide that specifies the use of a specific temperature sensor with an output of 5v ...
0
votes
3answers
186 views

Can voltages be different if watts are the same? Does DC vs. AC change this?

I'm currently building a home in a van, it's my first tango with electrical engineering. I watched a video on voltages and amps and my understanding is basically like so: a battery is like a water ...
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2answers
49 views

Voltage of a sine wave given max wattage rating

I would like to test a speaker by giving a sine wave of 200 Hz. On the technical datasheet following are mentioned Sine Wave : 30W Maximum music load : 60 W Frequency Range : 40 to 2000 Hz ...
0
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2answers
574 views

Formula for heat wire Kanthal or NiCr Watt consume?

The input voltage is 220v in single phase. How many watt consumed for Kanthal A1 (heat wire) AWG18 for 30m at 1400 degree Celcius ? How many If I use NiCr 60 or 80 with AWG18 ? Does anybody know the ...
2
votes
1answer
76 views

getting more from batteries via series connection

Let's assume I have a 100W load. If I run this load on two 2000mAh 3.7V batteries in parallel then I should get a continuous run time of 8 min 53 seconds (given the 27 amp draw). However if I were ...
0
votes
3answers
75 views

Which current should I use to determine the Watt?

I am making a heated blanket and I have some troubles to determine the heat that will be generated. Resistance: Let say, I use this heated cable with a resistance of 0.3 Ohms/m*. If I am using 10m ...
0
votes
1answer
381 views

Requirements to power 3.5kVa inverter?

How many 200 Watt solar panels do I need to power a 3.5kVa 48DCV inverter for 24 hours if the load on it is 1500 Watts and the batteries are 200Ah, 12DCV each in a country with about 6hrs of sunlight? ...
3
votes
4answers
541 views

Does a 1 watt 660nm LED put out more radiant flux than a 1 watt 630nm LED?

Given two LED chips consuming same or very similar amounts of DC power, One emitting light peaking at 630nm, The other at 660nm, In terms of output of (but light irrelevant to the sensitivity of ...
0
votes
2answers
116 views

How do I correctly estimate heat output for heater wire

This is based on a problem that came up today. During the course of this problem I realized that I wasn't so sure I understood the relationship between wattage and heat produced. In the past we did ...
0
votes
2answers
113 views

Which component cannot handle the higher wattage?

First time posting a question, so hopefully I've stated all the required details. As the title is not very specific, here is an explanation of my project. I'm making a revised version of the ...
0
votes
2answers
1k views

Solar panel and 120mm Computer fan

Just before I start description my question, I would like to let you know that I am new at this. I am working on a solar air heater for one of my window. I've been researching and reading up on a lot ...
11
votes
6answers
2k views

Is it possible to step-up the output of a laptop USB port to 12 watts?

I've got a USB device that requires 12 watts to charge. My laptop appears to output less that that. My question is: Is it possible to step-up the output of a laptop USB port to 12 watts?
0
votes
1answer
645 views

How much power does a wireless mouse use? [closed]

I have seen many answers online to how much power the USB dongle linked to a wireless mouse uses, but nothing about how much power the actual mouse draws from its batteries. What is a ball-park ...
1
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1answer
69 views

Selecting continuous pull type solenoid

I own a Rail track master and it needs two pull type continuous solenoids. The age of this machine is from the 1950's and both of the previous solenoids were unidentifiable. These solenoids operate ...
2
votes
2answers
181 views

On Computing Power Consumption for a GSM system

I'm a software student trying to learn about embedded systems. I would like to build a low-power system that can send his coordinates by SMS and also receive SMS. Unfortunately I'm at level zero in ...
1
vote
1answer
52 views

Flash Bulb battery depletion

Extremely simple question for you. Probably beneath all of you to answer apologies for that. My camera's flash is rated in Watt seconds. My battery is rated in mAh . If my battery can output 1000 ...
3
votes
1answer
87 views

How long can I run my camera off this battery?

I have Ultramax NP7-12 12v 7ah specifications here: http://www.batterymasters.co.uk/ProductDocs/SLAUMXNP7-12-TECH.pdf My camera consumes 1.25 watts per hour and runs at 7.8 volts but can run between ...
0
votes
2answers
283 views

Powering SMD 5050 strip via LM2596 DC/DC converter

I decided not to order / use the power supply typically sold with SMD 5050 kits. I heard a lot of explosion stories regarding those dodgy stuff. I want to make my own (power supply to drive SMD 5050. ...
0
votes
1answer
162 views

Why are these LEDs listed as 3W when the forward voltage is 2.4V, and forward current is 700mA?

The title of this listing says 3W: http://www.ebay.com/itm/50PCS-3W-RED-80lm-640nm-LED-Plant-Glow-Light-Emitter-with-20mm-star-base-/221518318191?pt=LH_DefaultDomain_0&hash=item3393854a6f But ...
0
votes
1answer
76 views

Using 6x58W fluorescent lamps instead of 6x55W, what could possibly go wrong? [closed]

I'm planning to buy a fluorescent photography lighting head, but the manufacturer specified it uses 6x55W lamps, but I want to use Philips Graphica 58W lamps. 3 watts more per lamp, doesn't look like ...
0
votes
2answers
177 views

What wattage solar panel required for AC 1000 watts

If my house load is 1000 Watts AC/220V, then 1000 Watts DC/12V solar panels is not enough. What wattage solar panel would be required for AC 1000 watts?
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3answers
1k views

How many Watts DC are equivalent to 1,000 Watts AC? [duplicate]

How many Watts DC are equivalent to 1,000 Watts AC? For instance, my load in AC is 1,000 Watts 220V. Then, how much DC watts would an equivalent load dissipate in 12V or 24V DC system?
1
vote
2answers
113 views

Watts in Solar Panels

How does the amount of watts affect a solar array? The solar array I found is 14 W, so what would I encounter if I purchased an lower/higher wattage? I'm going to purchase an array to charge my ...
0
votes
3answers
100 views

How to determine wattages on an applications note schematic?

Specifically, I refer to Fig 18 on Page 14 of this datasheet for dual supplies. Really nice, really "simple" to use 2x40W power amp I want to try out. Unfortunately, I'm a newbie and their schematic ...
2
votes
2answers
150 views

Looking for batteries to power a project I'm working on

Sorry if this is really basic, but I don't really know much about power consumption and voltage. I'm building a sensor system with a small computer with a 19V, 65W power supply, as well as a cloud ...
0
votes
0answers
64 views

Choosing a suitable power supply for a Robotzone gear motor

I'm building a project using a DC geared motor that I purchased from here: Servocity I need to know the specs of the power supply that can be used with this motor. How much current do I need? There ...
3
votes
4answers
542 views

Why is 5V DC so common? [duplicate]

I have an arduino, beaglebone black, and an arndale octa board and they all work 5V DC (albeit different amp rates). Most of my electrical sensors seem to operate around the 5V range. Why is this ...
2
votes
2answers
1k views

High voltage cable cross section

What kind of power and voltage can the cable in the photo possibly drive and why is it composed of a lot of small cables? What if the diameter of the single copper cables were a little bigger? How ...
3
votes
4answers
468 views

Voltage Divider DC 1000W for LED

I´ve done some research but not clear solutions are given to this problem, so I will post my case here in case somebody can help. Thanks in advance. I want to use a DC power supply to power up 121 ...
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votes
1answer
132 views

A question on Wattmeter [closed]

Wattmeter is an electric instrunment containing a resistor and an inductor.Then why are the watt-meter readings in KVA and not in KW?Is there any specific reason?