I usually find that E=σ/2ϵ0 is being frequently used but we hardly use E=σ/ϵ0.

When can I directly apply the equation E=σ/ϵ0 ?]]>

I have a small confusion regarding the formula that calculates the luminous flux of a light source, which is given by:

View attachment 114990

(See this Wiki)

The ##\bar y (λ)## is the so-called luminosity function...

Lumens and the Luminosity Function]]>

So the Bernoulli's EQ comes from conservation of energy. From the figure, I see that if Force 1 is greater than Force 2, the water will move to the right.

The distance Force 1 travels gives work of F

Trouble understanding energy aspect of Bernoulli's Equation]]>

Infact during isochoric and isobaric processes $$Q_{isochoric}=n c_v \Delta T$$

$$Q_{isobaric}=n c_p \Delta T$$...

Does efficiency alway depend on reversibility of the engine?]]>

strength of materials in a reinforcing being for garage]]>

can one cathode transfer electrons to multiple anodes]]>

the key area I wish to analyse is bar path in a squat and deadlift.

the work done against gravity is independent of path?

a lifter can either have a straight as possible body path and deviate the bar path or the lifter can alter his...

physics of moving heavy objects]]>

I'm working on a project where I am dropping an arduino with an accelerometer from ~100 ft in the air to measure it's acceleration during free fall and at impact. I need to compare my collected data with predicted models.

I have the model for free fall (just...

Modeling Acceleration at Impact]]>

An electron accelerated through a pd of V volts will have a K.E = eV. Why isn't the K.E less than this considering that some of the work done by the field has been radiated as electromagnetic waves by the accelerating electron ?

All insights very welcome.]]>

Basic question - balance of forces...?]]>

Electric potential problem]]>

I've been doing some reading around and have come across the idea that light slows down in an dense medium as a result of the photons moving tough other particals with a slight delay however they retain all factors about them selves apron...

why do photons pass through particles with a delay]]>

Chief Ray Angle and Field of View]]>

I've determined and calculated the density, specific heat, thermal...

How to calculate heat dispersion through a solid copper rod?]]>

Reversibility of physical law]]>

I need to know a bit about lightning/discharge, in a small scale ofcourse.

I have the impression that we can somehow (with a battery) charge a metallic tip and then if we put another metallic tip close enough, a lightning will be created. Is this correct?

In addition, I would like to...

Lightning movement]]>

- I know that paul traps confine ions with the help of rapidly switching quadruple electric fields, I've heard that paul traps actually force the particle to move to the center where the electric...

Problem understanding Paul traps]]>

Why don't guns kill the shooter?]]>

Question: Is this the same principle as probability wave which when observed reveals a particle?]]>

A Question about Hooke's Law...]]>

Doppler effect formula confusion]]>

Image FFT and lens MTF]]>

Scenario: a motorcycle is travelling down a straight highway at 100mph in 6th gear and needs to perform an emergency stop. The weather is clear and road...

The physics of braking on a motorcycle (manual transmission)]]>

The aim of my experiment is to calculate the magnetic field from the temperature...

Induction Heating]]>

Beam-powered propulsion - keeping the beam focused]]>

i apologies at my lack of knowledge...

How can an object move without acceleration?]]>

As my first post here I would like to open with a situation I have been struggling with

I have attached a simple diagram of my problem

I have 2 cylindrial N52 neodymium magnets axially aligned with each other with opposite poles facing each other....

Neodymium magnet partial shielding]]>

I leaned that using a sterescopic cameras (generates 2 photos) one can measure the distance to any object in the image produced by the camera.

For example, if I take a picture of a lamp post using a stereoscopic method, I can determine the Distance from the camera to the lamp...

Stereoscopic Images and Distance Between Objects]]>

is this possible? and if yes does it need electrolyte at the anode in the middle and how to apply it?]]>

Why is Qir < than Qr? Carnot cycle and change in G]]>

I have a question about electric elements and their corresponding voltages. I am looking at powering a 1500W 120VAC element out of an ordinary kettle with a DC voltage supplied by solar panels.

So, from what I understand, 120VAC represents the RMS voltage meaning that it would require...

Electric Element Voltage Specifications?]]>

I need any other tool: hypothetical speeds of ships, trigonometry, vectors, trajectories, any tool that is necessary...

Math tools in a travel to Alpha Centauri?]]>

Cherenkov Radiation and Non-Dielectric Materials]]>

in terms of oblique collisions, COM frames and laboratory frames, is this statements ALWAYS true?

"The scattering angle of the first particle in the laboratory frame is

Please elaborate if you know, thanks in advance!]]>

In my 4th year I got interested in cfd while doing a flat plate case. Fast forward to after grad and while I am looking for a job(Still looking :( ) I have been playing with Linux and open foam. I looked into astrophysics and plasma physics and such as they interest me to. So...

Are CFD codes like OpenFOAM used in other realms of physics?]]>

Lightbulb in series question]]>

I have a question for you guys and gals. I am working on a Desalination project and am ironing out questions about efficiency. What would be the most efficient temperature to evaporate water? 50, 100, 110 degrees? Does it make a difference, or is the energy required to evaporate a fixed...

Most efficient temperature to evaporate water?]]>

Lorenz Gauge]]>

Are continous Spectrum actually discrete?]]>

I have a 10 cc syringe connected to 3/32" tubing with leur lock and at the very end, it is...

How does tubing size affect pressure of syringes?]]>

Contrails -- What do we know?]]>

Helicopter torque]]>

Does anyone know of any fluid that emits light when current is running through it?

Why?

To feed to a flower, apply low voltage and make it glow.

Florescent light isn't enough and bioluminescence isn't my area of expertise so turning a flower into a LED is going to be my approach.

All tips...

Fluid that emits light when applied voltage, got tips?]]>

Looking at this I understand the the wire will experience a lorentz force because the...

Lorentz Force on a Conductor]]>

Looking for guidance on electrical impedance]]>

If we have a positron and an electron coming together and annihilating, we can always find a frame in which the net momentum is zero, which would suggest that a single photon can never be produced in such an interaction...

Annihilation and production of bosons]]>

but the sensor gives me values in LUX which is the illuminance and i need to convert them to Candela

I found this formula in wikipedia but i didn't understand...

convert from lux to candela]]>

Can we then say that each electron on average on...

Estimating # of photons/electron from magnetron.]]>

Launching a particle at the highest point inside a sphere]]>

Will the sensors in a row be triggered at the same time? If they are, what does it mean for the field?...

Fields and motion]]>

But I'm not sure I grasp this completely. Why is quantum mechanics linear while...

Linear and nonlinear physical theories]]>

Getting straight to the point, what is the difference between

Please be as specific as you can.

Thank you.]]>

Humidity and discharge]]>

Calcuating retinal irradiance from the sun]]>

I am working on a senior project right now and I need some assistance with determining the torque required to rotate an arm with a propeller attached to it.

View attachment 196002

Any of the 4 arms can be rotated to control the direction of travel. The idea is the control system...

Senior Project - Quadcopter with Rotating Arms]]>

$$\nabla \cdot \bf{E} = 0 \\ \nabla\cdot B=0 \\ \nabla \times E=-\frac{\partial B}{\partial t} \\\nabla \times B=\mu \epsilon \frac{\partial E}{\partial t}$$

Wave equation is $$\nabla ^2 \bf{E}=\mu \epsilon \frac{\partial^2...

Solutions of wave equation but not Maxwell equations]]>

What does it mean for a particle to vibrate?]]>

I know a capacitor in a circuit acts as a break when it is fully charged, but does the battery continue using energy to keep the...

Does a battery exert energy keeping a capacitor charged?]]>

for the reflected p-polarized light

\begin{equation}\label{a}

\frac{I_{p_{refl}}}{I_{0p}}=\frac {\tan^{2}(i-r)}{{\tan^{2}(i+r)}}

\end{equation}

and for the refracted one is...

Intensity of p-polarized light through stack of plates]]>

I don't get why there is a positive and negative electrode and what they do]]>

I am wondering if there is going to be no contact collision due to the the kinetic energy being...

Rutherford scattering and momentum]]>

Function of the Electromagnetic spectrum]]>

It's about constructor theory, something that I wouldn't normally...

Will Constructor Theory achieve its' claimed Potential?]]>

I dont understand why compressible flow needs to have another constraint of energy equation while incompressible flow only satisfies continuity and momentum equation. And how is this energy equation related to...

Why incompressible flow does not satisfy energy equation?]]>

is still valid in dynamics, with rapidly varying sources? We know that a rapidly varying charge here gives a flux...

Maxwell eqs. - integral formulation in dynamics]]>

How to measure the output of a generator]]>

I'm starting to work with a mini X-ray tube provided by Amptek. I want to use it to calculate the efficiency of a detector i'm going to use latter, so knowing the total flux the tube emmits and measuring the flux the detector receives, that should be enough (both data normalized to...

X-ray tube flux and my experimental test setup]]>

View attachment 195065

Why do they differ?]]>

Also, a slightly *crackpot* follow up question -...

Constant frequency of light and connection to QM]]>

My question is about the heat sinks (cold side) used in some dehumidifiers. It appears that thick, well spaced fins are used, as opposed to a larger number of thin fins, which I would expect to provide better heat transfer.

View attachment 195005

Am I right in assuming that...

A question about dehumidifiers and condensation]]>

From my limited understanding, antimatter can only react with its anti-particle....

Anti Proton - Non Proton reaction]]>

Inductor leading lagging voltage-current]]>

Moment of inertia dynamics]]>

checks and balances question]]>

##A## is inside one of the charges (never mind how)

##B## is sitting at the laboratory

In the lab reference frame we accelerate the particles. According to ##A## there will be only electric attraction or...

Thought experiment: charged particles]]>

I encountered a fairly straightforward problem involving fluid dynamics, but the result I got is very confusing and I seem not to understand where I got wrong.

This is the question:

A rectangular flat-bottom barge with a bottom area A=50 m2A=50~\text{m}^2A=50 m2 is loaded so that the...

A Fluid Dynamics Problem with Confusing Results]]>

Laminar and steady flow(Distinguish)]]>

I need to find out the forces acting on an anchor point]]>

In Feynman Lectures on Physics, there is a chapter about the conservation of energy. The...

Feynman explanation of gravitational energy]]>

This is all based around the double jump idea from games... Air is a gas and gases have resistance so it makes scene if you could put enough force in to a spot you should be able to be...

How much force would it take to jump on air?]]>

I'm currently working on a project alongside others who are interested in the topic of searching for wavelengths beyond the EM spectrum. We've been through countless piles of literature and seem to have a mixed opinion. Our question is simple (ironically):

Beyond the EM Spectrum]]>