Power Definition and 998 Threads

In my study of electrical engineering I have been told that the voltage across a resistance is V = IR. If I connect a resistor R and a power supply of 5V 2 A then how does ohms law work here? I could change R to anything I want but the source would stay at 5 V and 2 amps regardless of what I do...

:cry:

I'm currently researching if I could implement some wave energy into my small scale hypothetical project. I've identified some commercial models, namely Seabased and SINNPower, and I assumed that they would have approximate values of power output given wave period, height (among many other...

Force along the horizontal would be T cos(theta) Frictional force (which is in the opposite direction )= μmg So net force in the direction of velocity = Tcos(theta)-μmg P= [Tcos(theta)-μmg]v But this is not so, the right answer is given to be Tvcos(theta). Why should we not consider the...

P=W/t W=Q= mL = (100x 80x 4.2)/1000 (kg x J/kg) = 33.6 t= 1 minute= 60s P= 33.6/60= 0.56 watt... but the answer provided is 560J/s...?

Hi everyone, I want to rotate this (see attached image) platform at a speed of 20 RPM. To this end, I have to calculate the torque and power of a motor required. I have done preliminary calculations, however the numbers I'm getting doesn't seem right. For example, I'm getting that the torque...

Some areas of California are going to have their power turned off to prevent wild fires like they had last year. I don't live there, so lucky me. Its my understanding that some of the fires were started by wires blowing around and causing sparks in some way. Apparently, the power may be off for...

$$\frac{dP_{flow}}{dA} = \frac{1}{2} Re \{\vec{E} \times \vec{H^*} \} \cdot \hat{z}$$ since ##E_z = 0## everywhere ##\vec{E} = \vec{E_t}##$$\frac{dP_{flow}}{dA} = \frac{1}{2} Re \{\vec{E_t} \times \vec{H^*} \} \cdot \hat{z}$$ $$\frac{1}{2} Re \left\{\mp Z_{TE} \left[ \left(\hat{z} \times...

Given a balanced chemical equation, can we predict using computer models the maximum power of the chemical reaction? Thanks.

Hi guys, This month onwards our power distributor says that we only get powerfactor incentive when only we make the powerfactor leading and in between 0.95 and 1. Our industry fully consists of induction motor and compensative capacitors are provided but this month onwards we have to keep the...

Gravity batteries intrigue me. We are starting to develop them now. We currently are able to drop cement blocks and harness the energy that the kinetic energy releases. We are considering them as an alternative energy source to help the environment. Here’s a link for those unfamiliar with it...

Hi all ! I want a confirmation for this exercise please. The circuit: This is my try: https://www.docdroid.net/EFuTDMp/new-doc-2019-10-03-234340-1-converted.pdf -- Thanks

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.

Hello, I'm using a "TQ2SA-1.5V Panasonic 2 Form C AS Single side stable, 1.5VDC 2A DPDT NON-LATCHING SMD Relay" (specifically the coil side of this relay) that is rated for 1.5 volts that is connected in series to this circuit (as the last device in this circuit shown below), which in this...

Hello all: Doing some training in electronics repairing , and need to find some schematic diagrams for power amplifier , Google is not helping with that ,any suggestions where should I look Best Hagop

I've been told an effective induction stovetop needs to deliver about 1000W of power. I have magnet wire that can tolerate at most about 0.2A of current, and was planning on using a 60Hz wall outlet as my source (obviously I'll need to bring down the outlet current quite a bit). So the energy...

Summary: Suggestion on experimental research related to reactor for master's degree dissertation. Summary: Suggestion on experimental research related to reactor for master's degree dissertation. I have just started my master's degree course in Nuclear Power Engineering and decided to...

Summary: Am seeking help understanding why when I take my battery (50V max 44 nominal; 15aH capacity; 12s5p) and attempt to step down the voltage that sometimes it works and sometimes not... Hi all, New to forum. Chemical engineer seeks help from electrical engineers... Thanks for reading...

Which equation do I use and why do I use it? I think it would be P = V^2/R, but why do we exclude current the from the equation?

Why we can't use radical to solve an equations with power greater than 4?

I'm thinking of implementing a metal disk-like probe in an Argon plasma which is powered by RF. Therefore I need to know a metal that's least reactive with the plasma. Does molybdenum meets this requirement?

My attempt-: So the resistance is coming to be negative.Can anyone tell me my mistake.Thanks.

So I know the formula " W_turbine = m_flow rate * (H_in - H_out) " BUT is there any formula that utilizes the turbine volumetric flow rate (m^3/sec) at the outlet? The following data is available, I just need the formula... P_in= 2.36 Mpa P_out= 0.95 MPa m_flow rate= 0.02 kg/sec eff_turbine= 70...

hi sir i have 1100 watt motor and i want to rotat the fly wheel from rest to 1450 rpm.i want to know how big should be the flywheel to rotate at the motor 1100 watt and to get extra energy 700 joule or more than if possiable best regard thnx

I have an inductive load (120 volts AC at 0.5 amps AC at 60 Hz, 0.9 power factor before correction) that is a connected to the grid. I have been trying to increase the power factor above 0.95, but no matter how much I tune the power factor correction capacitors I cannot increase the power factor...

I want to know what's the flow rate (in kg/s) of saturated steam at 5 barA pressure to the turbines of a 250 kW power plant.

why does a polywell not generate net power? what are the loss mechanisms?

A fully electric mining truck has been built that does not burn fuel. It has a 600 kilowatt-hour battery pack, and they need to discharge about 200 KwH of that every night to keep from overcharging it. The secret: It's loaded at the top of the hill, and unloaded at the bottom. The regenerated...

Summary: Hi there On a 12VDC transformer we use at school. Is the positive terminal +6V above ground potential and the negative terminal -6V below ground potential? Thank You Hi there On a 12VDC transformer we use at school. Is the positive terminal +6V above ground potential and the negative...

Hi everyone! Awesome forum! I'm doubting myself on a problem about inverse square law. I'll change the actual values from my homework problem as I want to check that I have the right idea rather than the specific numeric answer. If I am using an inverse 2.5 power law and know the power at 100m...

I have been trying to calculate what retinal irradiance value I get with a 1 blue LED system. Since the manufacturer didn´t give the spectral distribution information, I will approximate LED as a monochromatic one (using the 460 nm peak). From the datasheet, the LED intensity range goes from 6...

Hi, So I have a uni project and were required to design a jockey wheel and corresponding power screw. We're given a maximum load and have to do the relevant calculations, moment of torque, efficiency etc. My question is I don't understand how to take the given maximum load and find the relevant...

So I've basically built a robot that has a lot of servo motors. 14 of them can draw up to 3 amps each(max)(usually 1 amp average) at 4.8 to 7 volts. What's my best option to power it? The power source doesn't need to be connected to the robot, so weight shouldn't be an issue. My best guess is...

Exelon the current owner of Three Mile Island Power Plant will shut it down in about two weeks. This is 15 year short of its current license expiration date. The reason supposedly is the cost of operation since methane is currently so cheap. Exelon tried to persuade the Pennsylvania...

Hello, as part of the study of fields with central forces, I came across with fields called power law, defined by F = - K/r ^ n u (u is radial vector passing through the origin O) I would like to dismiss case n = 2, which refers to the Newtonian fields whose study was exhaustively conducted in...

Hydroelectric power, effected usually by damming a river, is ordinary considered an example of energy produced by gravitational potential. However, from an ultimate perspective, hydro power is actually an example of solar power. Water must drop to a lower gravitational potential to extract...

A coal fired steam plant takes in feed water at a temperature of 70°C and produces 15 tonnes of steam per hour at a pressure of 60 bar and temperature 400°C. The fuel consumption rate is 1.5 tonnes per hour and the calorific value of the fuel is 40MJkgˉ¹. Determine the power rating of the boiler...

I have a home appliance that should be plugged into one single wall socket because it's energy consuming, and shouldn't share with other appliances by common sense. However, due to some practical problems, I can't plug it directly into the wall socket. If I use a power extension board (i.e...

I have a socket on the wall , because of the size of the adapter, the switch on the socket is always stayed between "ON" and "OFF" while it serves and works. From the electrical point of view, is it a complete circuit inside? is there any partial complete circuit which may be a problem?

If $y=(x^3-cos x)^5$, then $y'=$(A) $\quad 5(x^3-\cos x)^4$(B) $\quad 5(3x^2+\sin x)^4$(C) $\quad 5(3x^2+\sin x)^4$(D) $\quad 5(x^3+\sin x)^4(6x+\cos x)$(E) $\quad 5(x^3+\cos x)^4(3x+\sin x)$ ok I am sure this could be worded better. but I think many students take these tests and are not used...

Hello all, I have designed an intake manifold for boxer-6 naturally aspirated petrol engine with 1:1 bore to stroke ratio and has a bore dia of 117.89mm and a volume of 7.8l as part of my master's project. The engine was to produce 450 bhp @ 6500 rpm and I did set a rev limit @7500 rpm. The...

I figure I could connect a high voltage source with a high impedance, and verify that it clamps that voltage. The easy way would require very careful consideration to keep it safe - that would be to use a 220V outlet connected through a 220K Ohm Resistor on each leg. Apply the current limited...

Summary: If SCRAM completely removed all moderator from the reactor, would decay heat still be an issue? My understanding of how decay heat occurs after shutdown in large scale Nuclear Power Reactors. Is that Beta Decay causes residual Neutron activity at a small fraction of the operating...

I was trying to calculate the EMFs from power lines, just to see how they correspond to transmission line right of ways, and got a little stuck calculating the electrostatic E-field (-∇V) from power lines. I know it is dependent on the charge distribution on the power line, which is in turn...

Summary: How do you determine the armature current during the braking time? For a simple permanent magnet DC motor with a known resistance and inductance in series with the armature, I would like to know how to determine the armature current if there was an electronic motor drive controlling...

Intuitively I fell like AC would lose more power long a long power line than DC. I will use a model to explain my perspective. Let me model a wire as a long straight, non-frictionless tube, about the diameter of a marble, filled with a row of marbles that are each connected to the one next to...

Hello there! So confused here, I tried to do some calculations with my power generation experimention. In terms of energy input, the energy output is lower. But in terms of power input, the power output is way larger. Thanks in advance! Cheers!

My question is: is the resolving power of an array of radio telescopes a quantum or a classical effect? The increase in resolving power of a single telescope, as aperture size increases, is easy to explain in terms of Heisenberg's uncertainty principle. But when we go an array of telescopes are...

(Just as clarification on what I am doing, I am attempting to use MATLAB to create PSD plots of time series from pressure and accelerometer sensors. Wave gauge sensors might still be helpful for me. I did not discuss accelerometer sensors in the post but maybe I could figure it out if I get the...

Hello all PF members! I was wondering about the power dissipated by resistor at high frequency which is: ##P=Re\left \{ U\cdot I^{*} \right \}=Re\left \{ \frac{\left |V^{+} \right |^{^{2}}}{2\left |Z_{c} \right |}\cdot (1-\left |\Gamma \right |^{2} )\right \}##, (1) where: ##Z_{c}## -...