Power Definition and 998 Threads

All of my working out is attached with the photos, I'm struggling to do anymore as the tutor hasn't explained anything like this yet. Any help would be much appreciated

Hi, So the main question is: How to deal with power loss in E-M waves numerically when we are given power loss in dB's? The context is that we are dealing with the damped wave equation: \nabla ^ 2 \vec E = \mu \sigma \frac{\partial \vec E}{\partial t} + \mu \epsilon \frac{\partial ^ 2 \vec...

So if I have a source of 5V and 20 amp then the maximum power I can get from the source will be: $$ P_{max} = 5*20 = 100W$$ but my load can only take in 5 watts, it will blow up. But, does this have to happen or does my load only take what current it needs? My guess is that the load takes in...

This is the first part of the problem, which I solved. Now to the second part which I can't manage to find the equations I need to use. Problem: This plant is connected to a 20/0.4 kV transformer of 250 kVA power, through an XP00-A cable (4x150 mm2, IN=300 A, Z1=0.26 Ω/km). a) Calculate...

Hi all, The power factor correction unit for one of the buildings that I am working on needs maintenance. The service report recommends replacing the existing 25 kVAr unit with 2 x 12.5 kVAr units as "the demand on your site according to the data supplied shows us that at most there is only...

OK, so I tried to relate the equation P=Fv to the given equation that Pave^2= 3(Pftp^2)/Nh. I put Nh in terms of distance to satisfy the requirement that the answer should be in terms of Pftp and distance by saying Nh = distance/Vave. I also substituted Pave with Fvage. (FVage)^2 =...

This is not a homework question, but I am interested to calculate the power that can be extracted to perform useful work in two similar circuits. I have been told that it should be the same but this is not what I get. Consider a voltage source as a fixed voltage source in series with an...

∑(x2n/(2nn2)) We use the ratio test: ρn = |(x2n2/(2(n+1)2)| ρ = |x2/2| ρ < 1 |x2| < 2 |x| = √(2) We investigate the endpoints: x = 2: ∑(4n/(2nn2) = ∑(2n/n2)) We use the preliminary test: limn→∞ 2n/n2 = ∞ Since the numerator is greater than the denominator. Therefore, x = 2 shouldn't be...

I just thought up a little problem and wondered whether anyone could advise as to how to go about it! On a flat course, suppose a cyclist might be able to maintain 300W for around an hour. This gives a total allowed energy expenditure of ##1080t \text{ kJ}##, where ##t## is measured in hours...

Moved from technical forum section, so missing the homework template Let x be a real number. Find the function whose power series is represented as follows: x^3/3! + x^9/9! + x^15/15! ... I see that there is a connection to the power series expansion of e^x but am having difficulty finding...

I was curious in regards to a homopolar motor where the energy imparted into the rotor comes from if the energy input is say 10v at 1000 amps and there is 10v 1000amps output. Aswell if the effect of the magnetic field produces a different power on the rim of the disk vs the input from the...

At the exam i had this power series but couldn't solve it ##\sum_{k=0}^\infty (-1)^\left(k+1\right) \frac {k} {log(k+1)} (2x-1)^k## i did apply the ratio test (lets put aside for the moment (2x-1)^k ) to the series ##\sum_{k=0}^\infty \frac {k} {log(k+1)}## in order to see to what this...

Hi I am usually living off grid in simple huts in remote locations in Asia. A few months per year (rainy season) I don't have enough sun to produce solar power. I need very little electricity. My 20w solar panel produces enough electricity for my needs (lighting + charging a few small gadgets)...

Hey everyone, So I'm trying to figure out what could be causing this problem: I have a DEWENWILS Wireless Remote Wall Switch which takes a 12V battery 60 mAh(23A battery), when I replace the battery with a 12V 500 mA DC power supply, the unit stops working properly. I'm able to use the Power...

Want to know how to get the actual power the pump needs. I can measure the flow rate by the flow meter and count the revolutions of the pump. But selecting the proper motor for the pump would be a problem. So I want to know how to determine the power of the rotary lobe pump and generate the...

I am trying to determine the flow of mechanical power through a structure like a drive shaft or even a simple lever. The components of the Cauchy stress tensor, ##\sigma_{ij}##, have units of force/area, so if I multiply by the velocity, then ##\sigma_{ij} v_j## would have units of power/area...

##\sum_{k=0}^\infty \frac {2^n+3^n}{4^n+5^n} x^n## in order to find the radius of convergence i apply the root test, that is ##\lim_{n \rightarrow +\infty} \sqrt [n]\frac {2^n+3^n}{4^n+5^n}## ##\lim_{n \rightarrow +\infty} \left(\frac {2^n+3^n}{4^n+5^n}\right)^\left(\frac 1 n\right)=\lim_{n...

given the following ##\sum_{n=0}^\infty n^2 x^n## in order to find the radius of convergence i do as follows ##\lim_{n \rightarrow +\infty} \left |\sqrt [n]{n^2}\right|=1## hence the radius of convergence is R=##\frac 1 1=1## |x|<1 Now i have to verify how the series behaves at the...

##\sum_{n=0}^\infty (-1)^n \frac {x^\left(n+1\right)}{n+1}## for x=1 ##\sum_{n=0}^\infty (-1)^n \frac {1^\left(n+1\right)}{n+1}## i've tried leibniz test but i can only find that it converges why is this power equal to ##log(2)##? i've also tried with ##\sum_{n=0}^\infty\log \left (1+\frac 1...

Hi I need to create a electricity generator, I've got plenty of car alternators and car batteries, all are 12v. I know how connecting batteries in parallel / series, basically i could connect like 20 car batteries to have a 12v massive amperage power bank which would cause an issue with wire...

From the circuit I have: ##-v_b + v_a + V = 0## ##v_b - V = v_a## ##i_1 = (v_b - V)/R_1## ##I + i_2 = i_1## ##(v_b - V)/R_1 = I + v_b/R_2## From this last equation I get ##v_b = 10.8## and hence ##v_a = 5.8##. However, apparently that is wrong. (And hence my answers to #2 were all wrong as...

When calculating power, which is Work/time, do we consider NET work (work calculated based on net force) or just work done by the individual force that goes in the same direction as the displacement? If it's the first, then power is 3W. If it's the second, then power is 5W. Which one is correct?

I have heard that results form CMB experiments show a suppression of power at large angular scales. Can someone explain what "suppression of power" means in laymen terms in this context?

Hey, can you find me a power bank circuit which has 2.7V input?? Because I'm in a project which makes power bank with super capacitor, and you knows that we can't input voltage above the maximum voltage of capacitor, right? You can refer this video. Thanks.

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...

For those unaware of multifactorial notation, it should be noted that there are some common mistakes made when first being introduced to the notation. For example, ##n! \neq (n!)!## and ##n! \neq (n!)! \neq (n!)! \neq ((n!)!)!##. Just to make sure we're all up to speed, here's a quick run down...

Hello, I have been reading about impedance matching as being the main requirement to ensure maximum "power" transfer from one part of a circuit to another: the two electric systems ##A## and ##B## need to have complex conjugate impedance so only 50% of the energy is reflected back at their...

Consider ##f(x) = {^{\infty}x} = x \uparrow \uparrow \infty## and ##g(x)=p_{x}###, where ##p_x### is the primorial function and is defined such that ##p_n### is the product of the first ##n## prime numbers. For example, ##p_{4}### ##= 2×3×5×7=210## Let the point of intersection be defined as...

Human power 97 watts? 2000 kilocalories is the average human need per day. 2000 kilocalories is 8373.6 kilojoules divided by 86,400 seconds in days = 97 watts.

Hi all. I made a program of DFT, so I made the power spectrum of a sin wave. This is the sin wave I used. All data number ##N=100## and the frequency of sine wave is 4.5Hz. And the power spectrum is this. The wave number is not integer so the spectrum has the side lobe. But I think this is...

I don't know which part gets wrong

My Attempt So Far: 1. Write down all information: Q=10m³ /min h=75m 2. Change 10m³ /min to m³ /s 10m³ /min × min/60s =1/6 m³ /s 3. Change Volumetric Flow Rate to Mass Flow Rate ṁ=ρQ ṁ=1000kg/m³ × 1/6 m³ /s ṁ=166.67 kg/s 4. Apply Potential Gravitational energy but replacing the Mass with...

Hello everyone, I was thinking how to cancel the class B crossover distortion, may I suggest to discuss an interesting variant. Let's start from this: - there is crossover distortion (and no current protection). The signal source is "full voltage, zero current". Let's make it "full current...

I started with calculating the Ep and Ek of the helicopter and got this: Epi = 490m Eki= (1/2)(400m) Epf = 12740m Ekf = (1/2)(1681m) I don't really know where to go from there. Do the unknown mass variables cancel out? I'm lost!

is there any equation to find the work done, power and efficiency of a multistage compressor with a summation of calculating the power as so, instead of calculating individual power and summing at the end. any citiations is also good to know. thanking you, with regards, vishnuvardhan

Equations: Pr : Pm : Pc = 1 : 1-S : S Total Power into rotor: Pr=I'22R'2/S Mechanical Power Output: Pm=I'22R'2(1-S)/S Power loss in rotor: Pc=I'22R'2So I'm a little skeptical of my answer here. Seems a little too easy, which normally means I've missed to mark by about 100 miles. Attempt...

I have an ODE: (x-1)y'' + (3x-1)y' + y = 0 I need to find the solution about x=0. Since this is an ordinary point, I can use the regular power series solution. Let y = ## \sum_{r=0}^\infty a_r x^r ## after finding the derivatives and putting in the ODE, I have: ## \sum_{r=0}^\infty a_r...

Dear all. I have made the power spectrum of Poisson noise(expected value ##λ=2##), and it becomes like this I think this is not good. I don't know why the power is so high when Random variable(x axis) is 0. I tried another expected value version ,but the result didn't change. so I would like to...

I am going through "Circuit Analysis for Dummies". On pg 18, it says, "If you calculate the power dissipated as 0.1 watts, then a 0.25-watt resistor can handle this amount of power. A 0.125-watt resistor should be able to handle that amount as well, but when it comes to power ratings, err on the...

Summary: Derive the formula of power spectrum from Discrete Fourier Transform. Hi all I don't know where should I post this, so if I am wrong, I apologize.(But this is almost math problem so ) I would like to know the calculation process when derive Eq(6.3) in this paper. Eq 2.4a is...

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F(net)=F(app)-F(resistance) ma=F(app)-F(resistance) (1.5*10^3)(16.67)=F(app)-600 25005=F(app)-600 P=ΔE/Δt P=25005/6 P=4167.5 W I got the incorrect answer (because I didn't take into account the resistance?). I am also confused about which Force value to use for the...

1/f = 1/dₒ + 1/dᵢ = 1/1.0 + 1/0.33 = 4.03 m (focal length) Power: 1/4.03 m or 0.248 (0.25) *around to the2 decimal points? or leave it as a fraction? ((Did I do this correctly? I am not sure if this is correct and is it okay to be in meters not centimeters?)) Please let me know!

I've been playing around with Up-Arrow notation quite a lot lately and have come up with the following "thought experiment" so to speak. Consider the following function: $$f(x)=(−ln(x↑↑(2k)))↑↑(2k+1)$$ $$\text{Where }k∈\mathbb{Z} ^+$$ In the image below we can see some examples of what this...

Hi I would like to Derive the power spectrum of sinusoid.I tried like this. But It doesn't work. <Moderator: CODE tags added> #include <stdio.h> #include <math.h> #define pi 3.1415926535 FILE *in_file, *out_file; int main() { dft(); } int dft(int argc, char *argv[]) { char...

Im having a really tough time with this problem, I am assuming that in order for q'(z) to be a maximum, e^(-az/L)sin (pi(z)/L) must be a maximum. I believe this occurs when the derivative with respect to with respect to z/L is zero, which gives me z = 0.322L, but I am not sure if this is correct...

Attached is an example from my Tipler physics book of a determining the power delivered from a cars engine. I get the derivation(math), but am having some issues with the understanding/concept. Mainly, isn't Power=Work done/time. If so, they define the system as Car-earth. There is no external...

Ref: https://www.semanticscholar.org/paper/Design-and-Simulation-of-Different-Wireless-Power-Baroi-Isla m/dc19ecfde904964704777ab5adef96d5d6846f1f I couldn't find the working of this circuit so I guess it would be like: Initially transistor is OFF, so the current flows through Base, and...

I'm already stuck on A. I'm hoping once I figure that out the rest will just fall into place but be prepared for this to take awhile. I understand how to use Faraday's law to get the current or voltage of the system based off the movement of the bar but I have no Idea how to relate the rate of...

100mW = 20 dBm, that is then amplified by 2dB 20dBm/2dB = 10mW so power out of the amplifier would be 100mW+10mW =110mW?