Proportional Definition and 190 Threads

Many people have said that the noise that affects laser light is proportional to the square root of the illumination. But I can't find the formula. Can anyone help?

why is that the gravitational force proportional to product of masses why not sum of masses or something else .........

I am attempting to calculate the proportional luminosity of a fictitious star using surface area and temperature in kelvin. To what level of accuracy can I expect from the formula L ∝ AT^4? Where L = Luminosity, A = surface area and T = Temperature L ∝ AT^4 L ∝ 4π · (r)^2 · (T)^4 If I replace...

Why is resistivity inversely proportional to resistance for NTC semiconductors?

Can anyone help me? I know that's wrong, but i don't know where. Thanks for your attention so far.

Since the car starts from rest it’s accelerating. So, $$F_a-f_k=ma$$ $$F_a-\mu mg=ma$$ $$\frac{F_a-\mu mg}m=a$$ Now from second eqn, ##s=ut+\frac12at^2## $$s=\frac12\frac{F_a-\mu mg}mt^2$$ $$\frac{2sm}{F_a-\mu mg}=t^2$$ $$\sqrt{\frac{2sm}{F_a-\mu mg}}=t$$ I don’t think I am getting any where!

I have a proportional-only controller LED driver circuit - I need to fine-tune its ##K_P## to 10 for a significant input of -0.2 to 0.2 V in the steady state. In that case, should I use a potentiometer with 10:1 setting? The LED (actuator) can drive voltages between 0 to 4V, so I need to add...

Image above is the question. Below image depicts solution. if F1 is removed then the acceleration of that mass must be sum of accelerations of remaining forces. Right?? But answer says that acceleration of that mass is equal to acceleration of F1. I don't understand it. Can someone explain it??

There are optical crystals that can convert a small fraction of the incoming beam of light into light of different frequency. See the Wiki article, https://en.wikipedia.org/wiki/Spontaneous_parametric_down-conversion "Spontaneous parametric down-conversion (also known as SPDC, parametric...

I used the equation below and the attachment to rationalize. https://www.physicsforums.com/attachments/282163

Would you call it an inverse relationship or a linear relationship, what is the correct terminology?

First off let me say I am a bit confused by this question. Searching for some references I found the following related to the KG propagator, given by (P&S, chapter 2 pages 29, 30) Then they Fourier-transformed the KG propagator Is this what is aimed with this exercise? If yes, could you...

Hello, There is a thread related to this question however it was marked correct but doesn't look correct to me? https://www.physicsforums.com/threads/step-change-in-a-proportional-plus-integral-controller.961180/ I think I have it but it is quite different to other answers I have seen? I...

Hello, I found an old thread related to this question but it doesn't look correct to me so was looking for some guidance. I have equated Qo = (Q2+Q1*G) / (1+H*G) I did this by rearranging Qo=Q2+G(Q1-Q0*H) I then went on to the calculations and found before step disturbance: Qo=...

how does a 5/3-way proportional directional control valve VPWP work ? and Information about the 5/3-way proportional directional control valve plss. :cry:

I can't seem to find an answer to this: If the present level of greenhouse gas concentration were not to change, would the temperature of the planet continue to increase? Or would it level off? Or is a continually increasing concentration of greenhouse gases required to keep raising the planets...

Can I please ask for help with the following: Forces proportional to the sides of a quadrilateral taken in order act respectively along those sides. Prove that the resultant of the system is a couple whose magnitude is represented by twice the area of the quadrilateral. Not sure where to start...

Apologies if this is a question with a basic answer, I'm coming back to physics after many years of being away from it! I read somewhere that for longitudinal sound waves traveling through air, if the temperature increases by 1 degree celsius then the velocity of the wave will increase y 0.6...

I'm confused as I'm aware speed is directly proportional to the EMF, but is it proportional to the voltage as well? If the speed of a DC generator is halved and everything else is remaining constant the EMF will have so will the output voltage half

In the textbook Thermal Physics by Daniel Schroeder he says the following: However, I don't follow this argument. Let's say that G was the following: $$G(T, P, N) = (TPN)^{1/3}$$ Then $$G(\lambda T, \lambda P, \lambda N) = \lambda G$$ So $$G$$ is extensive, but $$G \not \propto N.$$

Hi all, I'm reading an article describing the D0 experiment at Fermilab during Run II. Proportional drift tubes and mini drift tubes were used to detect muons: can someone explain me the difference between these two kinds of drift tubes? Thanks Federica

Hallo guys,Im kinda confused about something and hope you can help me. Let me introduce you to it. we take a look on one Mechanismen to the spin hall effect, skew scattering effect. i just read that you can see this contribution only in the clean Limit. So that's really strange for me cause...

I understand the concept that a more energetic photon would cause more ionization events and therefore we can estimate the original energy of the incident photon. But what I don't get is that in practice, you don't get one photon entering the detector at a time, you get a whole bunch of them...

when we say one term is directly proportional to something for example if I say x directly proportional to y and I also say x is also directly proportional to z then why we multiply y and z when we say x is directly proportional to something whose value is yz.

Why does hysteresis loss cause heat and why the heat proportional the area of hysteresis loop?

I already tried plugging in values I saw from example problems and tried to find the correlation between the two solutions I would get, but thus far haven’t been able to find any. Maybe I’m overcomplicating this or looking at this the wrong way?

Hello. I'm a graduate student in electrical engineering, and I'm taking a class in semiconductor physics. My professor has used this equation for the energy of an electron in a semiconductor: $$E=\frac{\hbar^2 k^2}{2m^*}$$ This seems to imply that energy is inversely proportional to mass, i.e...

Hi, I'm trying to find an expression or phenomenon where a certain quantity is proportional to force squared or power squared. For example, we have Force ∝ acceleration and Power ∝ I². I'm not sure if my question is a legit. I was trying to understand something and this question came to my...

I was confused by the question below http://www.antonine-education.co.uk/Pages/Physics_4/Tests/Test%20on%20Fields.pdf if you look at question at question 1 section B same reasoning is used to answer this question as you can see the graph is a straight line?? but plotting r against T ^2/3 or...

Homework Statement (a) With the aid of a sketch explain how proportional action is produced in a pneumatic controller whose output is 0.2 to 1.0 bar. Assume that the controller is direct acting. (b) Show, mathematically, that the output is dependent on the difference between the measured and...

Homework Statement A vibrating standing wave on a string radiates a sound wave with intensity proportional to the square of the standing-wave amplitude. When a piano key is struck and held down, so that the string continues to vibrate, the sound level decreases by 8.0 dB in 1.0 s. What is the...

Homework Statement Figure 5 shows the input and output wave forms for a proportional plus integral controller. State: (i) the controllers proportional gain (ii) the controllers integral action time The attachment below is a copy and paste of the input and output wave forms I am given...

Homework Statement I'm having trouble worki out the transfer function of the block. Whats confusing me is the input of O2 input of 50. If that wasn't there I know the transfer function would be Oo/Oi=G/1+GH. Homework EquationsThe Attempt at a Solution

If Bernoulli's equation P + 1/2ρv2 + ρgh = constant, implying that pressure decreases as velocity increases, and the Venturi effect states that a1v1 = a2v, what resolves this apparent contradiction? The velocity slows as the cross sectional area increases, but a narrower pipe would have greater...

I hear somewhere explanation why kinetic energy is proportional to $v^2$ and not to $v^3$, for instance. https://www.physicsforums.com/threads/quadratic-forms-and-kinetic-energy.826884/ I wish to find reference for this. Now I find your thread with the same question and very similar answers...

Homework Statement 11.10 The acceleration of a particle is directly proposional to the time t. At t = 0, the velocity of the particle is v = 16 in./s. Knowing that v = 15 in./s and that x = 20 in. when t = 1 s, determine the velocity, the position, and the total distance traveled when t = 7s...

<Moderator's note: Moved from a technical forum and thus no template.> Hi, I am a junior in high school and future physicist. I have a problem (I am very curious) and would like for it to be solved as I CAN NOT figure this out! I was thinking about an object being dropped from rest from my...

I've always struggled with understanding proportional band - even after watching a number of videos trying to explain it. Now I've got a fan regulator that has a temperature sensor and a potentiometer. It works by sending a signal (0-10V) to the fan if the ambient temperature drops below a...

Homework Statement [/B] A 5 to 20 bar reverse acting proportional pressure controller has an output of 4 to 20 mA. The set point is 11 bar. Determine: (a) the measured value pressure which gives an output of 15 mA when the proportional band setting of the controller is 40% (b) the proportional...

Faraday's law states that emf is proportional to change in flux. The scenario I am using is a magnet is moved towards a closed loop. As it moves towards the loop, flux through the loop is increased causing a emf to be induced. Does I also know that a current is induced. So does that mean current...

Homework Statement [/B] Given a a log-log graph with 8 lines, you must determine the equation of each line in its original relationship. The slope of the graph (m) gives the power of the original relationship. Examples: if m = 2, 3; then y ∝ x^2, x^3, etc. if m = -1, -2; then y ∝ 1/x...

1. The task is to figure out if the buoyant force is proportional to the mass of the object that is being sunk in the fluid (the fluid in this case water). I had an answer and that the buoyant force is proportional to the mass, but my answer only took into consideration objects with the same...

Homework Statement Homework EquationsThe Attempt at a Solution [/B] I am having difficulty understanding the question statement . I do not understand how can body come to rest when velocity is directly proportional to time .As time progresses , velocity increases . Could someone help me...

hello every one, I want to simulate a proportional counter with soil sample in Srim. but I don't know how to put the beam into my source, I mean that how can define the position of ions in soil sample. because my beam arising from my soil sample. and my source actually is soil. if you answer my...

Degree of ionization is the number of particles which dissociate by the total number of particles. if that's the case then higher number of particles should mean higher number of particles which get dissociated. this should also mean higher the concentration the degree of ionization will also...

Homework Statement If we have object with mass 10 kg traveling at starting velocity of 50 km/s and one force of resistance that is equal to v^2 of object's velocity how can we calculate distance and time in which that object travels until it gets to velocity of 10 km/s.Homework EquationsThe...

If you were to look at a simple 2D or 3D static equilibrium diagram, where a mass is suspended by multiple ropes at different angles, my gut feeling is that there is a fairly simple proportion between the distance between the center of mass and the rope (the distance created opposite of the...

I don't seem to understand this formula. How there should a negative sign before the displacement.Can anyone help me out?

Homework Statement Show that Kepler's third law, \tau = a^{3/2}, implies that the force on a planet is proportional to its mass. Homework Equations 3. The Attempt at a Solution [/B] I haven't really attempted anything. I'm not sure what the question is going for. What can we assume and use?

A spherical snowball melts at a rate proportional to its surface area. Show that the rate of change of the radius is constant. Two ratios are proportional if they change equally and are related by a constant of proportionality? Not sure about this definition, but please correct it if you can...