Law Definition and 999 Threads

Homework Statement One of the reasons a single photon could not produce an odd number of electrons and positrons is a) energy would not be conserved b) unattainable photon energies would be needed c) matter would be created d) charge would not be conserved Homework EquationsThe Attempt at a...

While calculating the force between two charges , why we don't put minus sign with charge.

Homework Statement Homework Equations Right Hand Rule The Attempt at a Solution I am not understanding why the force is left. I can only figure out that the current in the solenoid is moving clockwise because of the right hand rule. From there, I see that the induced current might be...

So I have been trying to derive peukerts exponent based on assumptions I know this won't be accurate but I am curious about the data. So I don't know the time to discharge the battery so I guessed 3 Hours the capacity at a 20 hour rate is 40Ah meaning the manufacturer rated discharge current was...

Maxwell equations are composed of: Gauss's Law Gauss's Law for Magnetism Faraday's Law Ampere's law with Maxwell addition If you take out Faraday's Law.. can other laws re constitute it? Or are they independent? I want to know how the world would behave if there were no Faraday's Law. Note...

Homework Statement We have a circular loop of wire, with AB is another wire which is also the diameter of the circular loop. The direction of magnetic field is perpendicular to the loop, into the plane of paper. The magnetic field strength is decreased at a constant rate, without changing the...

Homework Statement How do I calculate the current I3? Homework Equations I know that I1 = I2 + I3 and that I2 = 0.4 The Attempt at a Solution So we have a voltage source of 3.7V I would've thought that the equation for a clockwise circuit be 0.4R2 - 3.7 - 200I3 = 0 which gives me an answer...

Homework Statement A uniform beam AOB, O being the mid point of AB, mass M, rests on three identical vertical springs with stiffness constants k1, k2 and k3 at A, O and B respectively. The bases of the springs are fixed to a horizontal platform. Determine the compression of the springs and...

I am reading Reinhold Remmert's book "Theory of Complex Functions" ... I am focused on Chapter 0: Complex Numbers and Continuous Functions ... and in particular on Section 1.3: Scalar Product and Absolute Value ... ... I need help in order to fully understand Remmert's derivation of...

Moderator's note: thread split off from https://www.physicsforums.com/threads/frequency-of-a-spring.959080/ I know that Hook's law applies for small changes in position (x). ( relative to equilibrium point ) For larger changes in x it doesn't work.

The Kirchhoff law of dependence of energy emitted from a blackbody only on wave length and temperature was demonstrated by Kirchhoff in a paper in the year 1859. The paper is in german naturally but I found it translated in english in a book of prof. Brace in 1901. A lot of time ago. But my...

Not many people understood his proof in class, and the textbook's proof wasn't very clear so we went by with other derivations online. Then he filled half the midterm with his method, so I'm trying to understand how he did things. Looking back it seems very similar to the proofs we found online...

Homework Statement We have a normal 6 sided dice marked from 1 to 6. There is an equal chance to get each number at every roll. Let's put 1&2 as A type, 3&4 as B type and 5&6 as C type. We roll the dice over and over until we get a number of every type. Let X be the number of rolls. We are...

Homework Statement Given two things spherical shells radii r1 and r2 with r2 > r1. The inner she'll is charged uniformly with a total charge Q1, while the outer shell with Q2. A) use gauss law to computer the electric field everywhere B) Use any method to calculate the potential everywhere...

Homework Statement It is clear that SOMETHING exerts a force on the conducting wire in a downwards direction. By Newton's 3rd law, the (field of) this conducting wire also exerts a force on something. Homework Equations Could the magnet be said to move upwards (and hence reading decrease)...

Hi - I have been trying to figure out how long an object takes to cool and I am just banging my head on the desk. Info: Metal object is placed into an oven set to 302F (150C). The object is 3' long and 2.75" diameter, and is solid metal (steel). The object is "baked" in the oven for 30 minutes...

Homework Statement For a power spectrum density fluctuations ##P(k) \propto k^n##, I need to find the scaling (with respect to ##a##) of the horizon wavenumber ##\frac{2\pi}{\chi_H}## in a matter dominated universe in terms of ##n##. ##\chi_H(a)## is the evolving particle horizon, in a flat...

Homework Statement Two blocks are attached to opposite ends of a massless rope that goes over a massless, frictionless, stationary pulley. One of the blocks w/ a mass of 1.5 kg accelerates downward at (3/4)g. A. What is the mass of the other block? Homework Equations There were no given...

Is there any source that how can I derive the Malus of ? Where there's two polarizer This is the equation $$I_{out}=I_{in}[H_{90}+(H_0-H_{90})]cos^2(θ)$$ ##H_0=1/2(k_1^2+k_2^2)## and ##H_{90} = k_1k_2## Also I need to derive the $$I_{out}=1/2I_{in}cos^2θ$$ using integrals Please help

Hi all I was hoping someone could help me understand Hookes Law. Hooke’s Law, states that Stress is proportional to Strain. The bit I am struggling to understand is that Stress is F/A and Strain is Change in Length/Original Length, so if Stress is proportional to Strain then shouldn't F/A be...

I think the real magenetic field is sum of the magnetic fields calculated in each cross section of solenoid with various angle and same center axis when i apply Ampere's law. (Imagine the cross section contains a part of center line of the solenoid) Please let me know why we don't do like that. :)

1. The problem is: Which charge will a sphere have if it has a diameter of 0.26 meters and produces an electric field of 1030 N/C in the surface? 2. Gauss Law3. I need the charge of the sphere but i couldn´t find any formula to calculate the charge given the distance (r) and electric field (E)

Hello everyone, I am planning to build a device to test Beer's law for a specific solution and obtain the molar concentration of the solution. Beer's law presumes that the input and output light intensities are related by an exponential law. I need to know: The sample path length ##\ell##...

Homework Statement The problem is basically about tow infinite parallel wires separated by a distance ##d## with equally strong but opposite currents. You have to calculate the B-field outside the wires (not the field in between them). Homework Equations Ampères law: ##\oint \mathbf B \cdot...

Homework Statement determine the electric flow through a square surface of side 2l due to a load + Q located at a perpendicular distance l from the center of the plane I really don't know how to answer this question .i need help guys Thanks Homework EquationsThe Attempt at a Solution I ended...

Considering classically a light ray in a medium with lightspeed ##c_1## and entering a medium with lightspeed ##c_2## moving with speed ##v## along let say ##y## in the plane of the interface, is it correct to obtain a very complicated formula, having even 3rd power of trigonometric functions of...

In the link: https://www.maa.org/external_archive/joma/Volume7/Aktumen/Polygon.html Why the law of sines is permitted here? What are the goals of the author to use it?

Homework Statement A) use gauss's Law to determine the electric field at all values of radial distance (0<r<infinity) from the center of a non-uniformly charged cylinder that is very very long and lies along the x-axis. The cylinder carries excess charge per volume ρ=[a]r^2 (the [] are supposed...

Homework Statement We have a uniformly charged, non-conducting sphere (charge per volume,ρ, and radius, R). Then a uniformly charged ruler (charge per length,λ, and length, d) is aligned radially almost touching the surface of the sphere. Determine the net force experienced by the ruler...

Hi, I have been trying to set up a funtcion of the temperature over time and I am doubting my results. In the system i have: Fig 1. The system is at rest. For simplicty I've considerd the ambient temperature to be same as T1. By knowing: Fig 2. yeilds: Fig 3. In my case B&C is at a...

"Gauss's theorem can be established as follows. consider an attracting particle of mass m at the point P, and let a cone of small solid angle ω be generated by radii through P. This cone cuts the surface at the points Q1, Q2, ... taken in order from P; the parts of the surface cut off by the...

Homework Statement You have a conducting sphere that is in equilibrium, it has a cavity in it with positive charge +q. If you bring another charge +q2 near the outer edge of the conductor does the total surface charge on the wall of the cavity, q(int) change? There is an image attached that...

In a chapter building up to the theory of plane waves my book starts by introducing time harmonic electric fields and defines a special case of Gauss's law.curl(H) = J + dD/dt curl(H) = sigma * E + epsilon * dE/dt if E is time harmonic and spacially dependent... E(x,y,z,t) let E' represent the...

I've attached the problem and my work. When I enter cos^1(6.890625) I get an error, but 6.9 is also not the answer and Does Not Exist is also not an acceptable answer. So where I am going wrong with this?

Homework Statement A spherical cavity is hollowed out of the interior of a neutral conducting sphere. At the center of the cavity is a point charge, of positive charge q. (picture attached) a)What is the total surface charge q(int) on the interior surface of the conductor (i.e., on the wall of...

I attend a trade school, majoring in HVAC (Heating, Ventilation, and Air-Conditioning). My instructor has given me information that seemingly contradicts what my textbooks tell me about Charles' Law. My instructor is not a scientist. I asked my instructor to reconcile the two seemingly...

Homework Statement From the Fresnel equations and Snell’s Law, prove that, when θ = θB where tanθB = nt/ni, (θB is the Brewster angle); (a) Reflection coefficient = 0 , and (b) transmission coefficient = n/n’ Homework Equations reflection coefficient = (ntcosθi - nicosθt) / (ntcosθi + nicosθt)...

Homework Statement Two small insulating spheres with radius 9.00×10−2m are separated by a large center-to-center distance of 0.545 m . One sphere is negatively charged, with net charge -2.35 μC , and the other sphere is positively charged, with net charge 4.35 μC . The charge is uniformly...

<Moderator's note: Moved from a technical forum and thus no template.> Is what I have done correct ? I want to find v(t) from Sigma F = m*a. I have gravity force mg pointing downward with positive direction and resistive force R = -b*v^2 pointing upwards with negative direction are acting on a...

Homework Statement A man walks 120m [S 23 E] Then turns and walks 60m [S 10 N] draw a careful sketch of this situation and then solve for the displacement, you do not have to solve for the direction 2. Relevant equation: Cosine law The Attempt at a Solution Solution attempt is attached as a...

Homework Statement Suppose that an electric field is given by E(r,t)=E0cos(k·r−ωt+φ), where k⊥E0 and φ is a constant phase. Show that B(r,t)=((k×E)/ω)B(k⋅r-ωt+φ) is consistent with ∇×E=-∂B/∂t Homework Equations ∇×E=-∂B/∂t The Attempt at a Solution I know I have to take the curl of E, but I'm...

Homework Statement Use Snell's law to show fresnel Eq 1 can be expressed as Eq 2 Eq 1 = (ncosθ-n'cosθ') / (ncosθ+n'cosθ) Eq 2 = (tanθ' - tanθ) / (tanθ' + tanθ) Homework Equations nsinθ=n'sinθ' (Snell's law) The Attempt at a Solution n' = nsinθ / sinθ' Substitute n' into equation and then...

Homework Statement Vectors A and B have equal magnitudes of 4.93. If the sum of A and B is the vector 6.79j, determine the angle between A and B Homework Equations c^2 = a^2 + b^2 -2abcos(theta) The Attempt at a Solution I just rearranged the formula above so that I could solve for the...

Homework Statement The following is the equation of ideal gas law, where p is pressure (Force/Area), V is volume, n is number of moles and T is temperature in Kelvin. What is the fundamental unit of R? pV = nRT A. kg^−1 · m^−2 · s^ 2 · K · mol B. kg^−1 · m^−4 · s ^2 · K · mol C. kg · m^4 · s...

I have been working a project of creating a simulation of thin-film interference in a 3D modeling program, Blender, to be able to create materials that would use its effects. While uncommon, I would love for it to be able to correctly calculate reflectance and transmittance when the incident...

The potential difference between two points is given ans the negative of integral of E(vector) <dot product> dl(vector) from initial to final points. Therefore, integral integral of E(vector) <dot product> dl(vector) from initial to final point should give the negative of potential difference...

Homework Statement Two small balls, each of mass 5.0 g, are attached to silk threads 50 cm long, which are in turn tied to the same point on the ceiling, as shown below. When the balls are given the same charge Q, the threads hang at 5.0° to the vertical, as shown below. What is the magnitude...

If I have a magnetic field describing a closed path it means that this closed path is surrounding a current, right? But if I have no current, is it the displacement current ? I'm thinking of a magnetic dipole, its magnetic field describes closed paths from its north to south pole, so is there a...

Hello, I'm new to the language of calculus. I am learning about Newtons second law and I'm trying to understand it's forms in calculus. Excuse my notation, just trying to keep it as simple as possible. F=m * dV/dt I know V= dx/dt My textbook says you can 'apply chain rule' to obtain the...

Homework Statement Consider a cylindrical parcel of air of area A and infinitesimal height dz. If this air parcel is to remain stationary, the difference between the total pressure forces exerted on its top and bottom faces must be equal to its weight. Use this information and the ideal gas...