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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1answer
37 views
450mA in CK1050 rotary switch
So i bought CK1050 rotary switch i now i realized that it's rated only for 150mA 250V AC/DC on the data sheet. I need to use it with 12V DC at 450mA so will it be safe? If you think the watts it ...
0
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2answers
46 views
What permanent magnet motor is the best for the bike generator? How to decide about wattage?
I am new here.. I would like to build my bicycle generator with permanent magnet motor similar to this one Bicycle Power Basics
Basically, I want to run my pedal cinema with a bike generator. I am ...
-1
votes
1answer
34 views
Can I use a power cord from a computer for an amp [closed]
I rented an amp for a keyboard but didn't take the power cord. I'm pretty sure a regular computer or computer monitor cord will fit. Is it safe? The amp says on it 175 watts. Also I have a power cord ...
0
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1answer
97 views
Watts and relation with A/V
I have a doubt about some numbers I'm getting in LiveWire... Can anybody explain origin of these values?
I believed that watts come from Amperes x Volts, but these ciphers are driving me crazy...
I ...
1
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2answers
62 views
What is the valid capacity ranges of Lithium Ion 18650 batteries?
I'm seeing wildly varying capacities that are seemingly fake on 18650 cells, such as these "9,800 mAh" ones on eBay, but are ~$1 / cell.
However, 'genuine' cells from Panasonic and similar name ...
-2
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2answers
125 views
What does it means 100v, 10A ,100W darlington transistor?
I want to know what is the relation between (100v, 10A) and 100W in darlington transistor or actually any power device like mosfet or bjt transistor
does that means I can use this transistor to drive ...
0
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4answers
174 views
10 Watt LED and LED Driver related question
I got a 10watt LED from Ebay but never thought that the driver and heat sinks are must-haves for this little master. When googled, I found several circuits of LED driver. But none of them are ...
0
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1answer
82 views
wattage consumption of three phase electric motor
i have a 5 hp motor in my factory . at load, it shows 3.5 ampere consumption ( when tested by a meter). is the consumption accurate? someone told me that 5 hp three phase motor will consume 7.5 ...
1
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1answer
160 views
On guitar amps, what is the difference between the two “watts” figures?
Disclaimer: I know nothing about electronics or guitar amps.
(Actually, I do know one thing: that "wattage" is synonymous with "volume" when speaking about guitar amps and since watts are measured ...
16
votes
3answers
2k views
Why is the power consumption of electrical lamps specified in kWh/1000h?
This is the box of a LED spot I just bought. I'm wondering why the power consumption is measured in kWh/1000h and not simply in Watts.
Edit:
The labeling standard can be found here. (Guide for the ...
1
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3answers
115 views
Why are some electronic devices rated for volts and some current?
Why are some electronic devices rated for volts and some current? Isn't total wattage what matters? Most seem to be rated for amps, and Tesla famously ran hundreds of thousands of volts through ...
0
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2answers
76 views
Difference between incandescent/fluorescent/LED wattages?
If the numbers on the 'light output' table at the bottom of this page (here) is correct, and if I have a lamp (like this) that has a maximum wattage of 60 and takes incandescent bulbs:
Does that ...
0
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2answers
550 views
What wattage heating element required for 500 degree Celsius oven temperature
i have 32 litres OTG oven which is of 2000 watts and can generate Max. 250 degree Celsius .
40 Litre capacity
2000 watts
OTG has 2 heating elements, one at top ...
17
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4answers
3k views
Whats does “hr” mean among “V” and “Ah” in batteries?
I have a battery which indicates 12V25Ah/10hr.
What does 10hr mean here? I guess "hr" stands for "hour".
But 25Ah already means if battery is fully charged and if I load 12V 25A (=300W) to it, it ...
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1answer
59 views
Calculate VA for a given wattage [closed]
How to calculate VA given a wattage say for example 300 watts.
1
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1answer
54 views
Performance comparison of dual core and quad core processors with same TDP
Athlon X2 340 (dual core) and Athlon X4 740 (quad core) from AMD have same architecture and both have same TDP (65W). They also have roughly similar frequency. Does this means that at full load, the ...
0
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1answer
70 views
Verification on Ohm's Law?
I'm building some Heated Motorcycle Grips and I think my calculations are off. Can anyone help me verify that for 10 feet of 20 gauge Nichrome 60 wire, I have the correct Ohms, Watts, and Amps for the ...
3
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1answer
53 views
Solid-state lighting [closed]
Background
Consider the following technologies:
100 lm/W OLED (2008, source)
303 lm/W LED (2014, source)
94 lm/W LEP (2015, source)
For growing food, the preferred measurement is ...
2
votes
0answers
41 views
How to determine wattage of a resistor I found [duplicate]
In general is there a way to know what the wattage rating of a resistor is? I have a large bin of resistors of varying resistances and physical sizes. I assume size correlates to wattage as a larger ...
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1answer
163 views
Replacement Power supply for Xmas lights! [closed]
I have hit these boards as a last resort hoping someone may know a solution....
I have some xmas lights, they are a roll of 50 and each light rated at 0.06w or 0.02A.
I have added 33 lights to it ...
4
votes
1answer
169 views
Resistor wattage measurement
I'm not an engineer professionally but I'm interested in. So my question is, how to recognise the wattage of a resister? And how to measure it using multimeter?
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2answers
120 views
I need to know what resistor i need for my expirement?
Im doing and expirement with electricity. Im using 120v input. I have my device i created (im not gona go into detail with what i made other than its a wireless electricity generator that im trying ...
1
vote
1answer
68 views
Amp Limitation on 120v Circuit
If an engineer needs to limit how many amps come out of a wall's circuit, how is this accomplished? I know that there is nothing preventing more than 15 amps from coming through my wall other than the ...
0
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2answers
62 views
What are my power requirements for my second resistor, and did I do my first's power calculation correctly for my first LED floodlight design?
I'm planning to build my very first DIY portable floodlight which will consist of a Cree XP-L V6 LED, heatsink+fan, and a 12V power source (two sets of a 8 C battery series in parallel).
I plan to ...
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3answers
119 views
How much mA to charge an iPhone
I'm building an iPhone solar charger and I'm not very good with electronics but I want to know how long it would take to charge an iPhone 6 fully. The panel I'm using has:
...
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votes
1answer
200 views
Powering a WS2812B strip
After always being interested in learning more about electronics, I figured LED-strips would be a great start.
I'd like to power a 4 meter WS2812B-LED-strip (60 LEDs/m). These run on ...
0
votes
2answers
102 views
what wattage 10 ohm resistor needed for 330mA at 3.3v?
I'm pretty new to all this. Please forgive me if this is an obvious question.
I am working with an ESP8266 module. They generally have a max operating current draw of somewhere around 250 mA. I ...
0
votes
1answer
57 views
Heating wire filament with low voltage high current?
Is it possible to heat nichrome wire with 0.5V 20A?
what is the different between heat produced by 0.5v 20A (10watt) and 10v 1a (10watt) ?
1
vote
2answers
676 views
Does a 24V inverter consume the same amount of wattage as a 12V inverter?
Let me clarify. I know how series and parallel setups work. I know that in series the voltage adds but the current stays the same. In parallel current adds but voltage doesn't.
But that doesn't ...
1
vote
1answer
237 views
AC Watts to DC Watts Calculation
Okay, so I'm new to the whole electricity field and I'm trying to get a handle on something so I apologize for any ignorance displayed here.
I've purchased a new graphics card for my computer and I'm ...
3
votes
2answers
574 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 ...
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1answer
97 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, ...
1
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4answers
524 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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votes
1answer
84 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
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4answers
2k 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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votes
1answer
243 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?
3
votes
1answer
299 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)}\$.
0
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2answers
54 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
767 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
92 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
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1answer
195 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
159 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 ...
0
votes
3answers
2k 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 ...
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votes
1answer
152 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
267 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
393 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
7answers
645 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
2answers
119 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
189 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
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3answers
798 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 ...
