What is Charge: Definition and 1000 Discussions

Some spiders are known to fly on the breezes by extruding silk strands (like web material) from their abdomen. This is commonly thought to be caught in the wind and carry them away. This would explain the occasional spider you might see drifting by when you are outside. Many (including that...

I have a simple two-part question, or two simple questions. 1. What is energy? 2. What is charge? The charge I'm referring to is the charge on charged subatomic particles. And atom's charge is defined by the number of electrons and protons present in it. But an electron itself is called a...

I am trying to understand why an accelerating charge emits radiation/electromagnetic waves but a uniformly moving one does not. I saw one video on Youtube where it seemed that it was explained by the fact that with a uniformly moving charge the Poynting vector was pointing 'in to the volume' -...

Coulomb's law states that the force between particles depends on their charge. But protons and electrons have equal but opposite charges. Shouldn't the formula simply have constants with the only changes required being the signs?

Hi I have read one excellent explanation on the question I am posting again, at another thread on PF, because I am not able to completely understand the concept. Please spare some more time. I need help to understand how an electric field due to an infinite sheet of charge can be uniform where...

I'm watching a lecture and the professor is talking about generic quantum states as |\psi> He's making the point that this state is very generic. It can represent anything. He references some examples like the polarization of a photon and the path of a photon and the spin of an electron...

1. Charge is distributed through an infinitely long cylinder of radius R in such a way that the charge density is proportional to the distance from the central axis: ß = A r, where A is a constant and ß is the density. (a) Calculate the total charge contained in a segment of the cylinder of...

If I try to calculate the electric field in the x-y plane of a ring of charge resting at the origin on the x-y plane, I keep getting zero. I start with Coulomb's Law. $$ dE(r) = \frac{1}{4\pi\epsilon}\frac{dq}{r^2} = \frac{\lambda R}{4\pi\epsilon}\frac{d\theta}{r^2},$$ in which ##\vec R## is...

If voltage is the difference in charge between 2 points, then why for a capacitor of a larger area or thinner dielectric cross section, do they say that it can store more charge given the same apppied voltage? Isnt voltage the difference in charge between 2 points? So if you can store more...

Homework Statement Griffiths' Introduction to Electrodynamics problem 2.10, Homework Equations Gauss' Law, ##\int_{S} \textbf{E}\cdot \textbf{dS} = \frac{Q_{\text{enc}}}{\epsilon_0}##[/B]The Attempt at a Solution It seems reasonable that the flux through the shaded surface and the front...

Homework Statement Suppose we have a regular n-gon with identical charges at each vertex. What force would a charge ##Q## at the centre feel? What would the force on the charge ##Q## be if one of the charges at the vertices were removed? [/B]Homework Equations Principle of Superposition, the...

Disclaimer: I am not a physicist, just trying to learn some parts of it in my free time. And I do not mean to propose any kind of "new-theory" with my question. I always thought that Maxwell equations in their differential form for B and E may be reformulated/updated to include a magnetic...

Homework Statement A pair of parallel conducting plates, each measuring 30 cm X 30 cm, are separated by a gap of 1.0 mm. How much work must you do against the electric forces to charge these plates with ##+1.0 \cdot 10^{-6} C ## and ##-1.0 \cdot 10^{-6} C##, respectively? Physics for Engineers...

Homework Statement I was doing the Milikan Oil Drop Experiment from a simulation this site: http://scienceclub.ucoz.com/index/0-109. I tried calculating the charge of the electron but it was from the real value. Oil Density: 920 (kg/m^3) Viscosity of Air: 1.81×10−5 kg/(m*s) Distance: 0.0025 m...

Homework Statement Homework Equations V = I R Q= CV The Attempt at a Solution When the switch is connected to position a : 20-106 * I = 0 ( KVL) Vc = 0 , because the switch is connected for a long time. I = 2*10-5 A When the switch is connected to position b : Q/(4*10-6) - 106 *2*10-5 = 0...

Homework Statement Defibrillation[/B] is a common treatment for life-threatening cardiac arrhythmias and ventricular fibrillation. The defibrillator applies a current across the heart (shown by the red arrows in the image below) for a short time (a few milliseconds), disrupting the arrhythmia...

Homework Statement [IMG]http://[url=https://ibb.co/dgUy6T]https://preview.ibb.co/iyqS0o/20180525_213806.jpg Since i only know the field direction, increasing go into page. Why the answer is C? Why the answer "a" ? The R and r on the pic is respected to what? Homework EquationsThe Attempt...

Homework Statement Homework EquationsThe Attempt at a Solution I know the units for V is J/C so #3 and #4 are wrong. But how do I determine the signs?

Homework Statement A charged polystyrene ball of mass 0.14g is suspended by a nylon thread from a fine glass spring. In the absence of any electric field the spring extends by 30mm. The polystyrene ball is then placed in an electric field that acts vertically upwards, of strength 200kV m^-1...

Hi everyone! I'm trying to solve the following problem: given the charge densities of carbon nanotubes and graphene, the charge density difference of 2 systems must be found. So I need to unfold in some way the nanotube and compare it charge density with the graphene's one. But how this...

Homework Statement Sorry, the post isn't about a single homework problem but rather something that I keep getting confused on. It's about calculating the electric potential of a spherical shell of uniform charge in two different ways. Homework Equations ##\Delta V=\int_a^b -\vec E\cdot d\vec...

Homework Statement Q1: There are two concentric spherical shells with radii ##R_1## and ##R_2## and charges ##q_1## and ##q_2## uniformly distributed across their surfaces. What is the electric potential at the center of the shells? Q2: There is an infinitely long hollow cylinder of linear...

Do the SM and Lambda-CDM lepton-era models predict that the electron’s isolated electric charge be equal in magnitude (to 12 significant figures) to that of the proton which is a composite particle? What makes that this identity in electric charge magnitude is so exquisitely ‘fine-tuned’? What...

Homework Statement A hollow conducting sphere with an inner radius of 5 cm and an outer radius of 6 cm contains a smaller sphere of radius 3 cm, located symmetrically inside the hollow sphere. The electric field strength at 4 cm from the center is measured to be 2400 N/C pointing inward. The...

Homework Statement Calculate the net charge on a magnesium ion which has lost two electrons. 2. The attempt at a solution I put 2+ as my answer and this is what I was told, but I don't understand what they mean by the following; That's a chemist's shorthand, not the amount of charge on the...

What does the negative sign tell?

I don't really know how to fit what i want to this template, but i'll try. The thing is that i wonder if anyone can explain to me step-by-step what happened in this solution, because i don't really understand it. Homework Statement There are two balls. Upper one(mass m, charge Q) hung on a...

Homework Statement Homework Equations ##Q=CΔV## ##V=IR## The Attempt at a Solution Is my answer correct ?

Reading a thread in relativity I would like to know more precisely about radiation from charge. 1 I put a charge on the table of my house. Gravity and table reaction force work on the charge. They cancel so net force does not work on the charge, thus no-force no-velocity cause no radiation...

Homework Statement Homework Equations Q = C ΔV C = ##\frac{ε A}{d}## The Attempt at a Solution A = π R2 Q = (π R2*ε V)/d Is my answer correct ?

Homework Statement Express the electric field E due to a point charge q at the origin in cylindrical polar coordinates. Homework EquationsThe Attempt at a Solution Know that E = q / 4*pi*epsilon_0*r^2 in the r-direction, which is the answer in spherical coordinates. How we we swap to cylindrical?

Is like currents of opposite charge attract or repel each other

Homework Statement [/B] I need to calculate de radiation field produced by a charge moving in a circular loop of radius a, considering the motion is not relativistic and zone of radiation (far field) .Homework Equations The scalar potential is: $$ V=\int \dfrac{\rho(x')}{|x-x'|}d^3x'$$ The...

Hi guys i have a question i want an answer to let say i have an object that is negatively charged and another object positively charge and i connected them with a wires to a light bulb will they generate electricity and the object never lose their charge let's they they have unlimited charges.

If mass is considered to bend space time fabric.. does electric charge bends anything?

Homework Statement Homework EquationsThe Attempt at a Solution These AR type problems are mostly tricky and debatable . To me, A is correct and R is wrong . Although electron is approximated to be a point particle , but I think if R is true , then A will be wrong . I think c) is correct ...

Homework Statement Homework EquationsThe Attempt at a Solution [/B] Sorry for the unclear image . There is a wire across the combination of 2μF and 3μF capacitors which means the two capacitors are shorted . The whole of 6V drops across the 1μF capacitor . In that case charge on the 2μF...

I am currently working on a piezoelectric shoe and the objective of the project is to charge a phone I am aware a phone is DC and piezoelectric disc generate AC I know I need a bridge rectifier to convert My question is: Would I generate more volts if I Use a bridge rectifier to convert AC to DC...

Homework Statement Homework EquationsThe Attempt at a Solution In the steady state , there will be no current through the two branches containing the two capacitors . The capacitors can be replaced by open circuit . I need to find potential difference across the two capacitors which will...

If the electric field of a line charge at a distance 'a' is µ/2Π ε0a (µ is linear charge density), then the potential at that point should be µ/2Π ε0 (since potential = electric field x distance). This means that the potential is constant at every point around the line of charge. Hence, this...

Hello everyone, "Does a charged particle radiate in free-fall?". I read many threads on this subject and I was surprised to find out that there is no unanimous "Yes or No" answer to this question. Here is an interesting answer from researchgate.net: The question is widely discussed in the...

Homework Statement Let’s say I have got a charge density $\rho (x,y,z) = \cfrac{C}{x^2}$ with C a specific constant. I want to know the potential on every point in space. How can I get an expression of the electric potential in terms of position? Homework Equations Gauss law/coulomb's law...

Homework Statement Suppose an object has a charge of 1 C and gains #9.38 ✕ 10^18# electrons. When another object is brought in contact with the first object (after it gains the electrons), the resulting charge on the the second object is 0.9 C. What was the initial charge (in Coulombs)...

Homework Statement Homework Equations ##E=\frac{kQ}{r^2}## The Attempt at a Solution The answer is "A".Right ?

Homework Statement Homework Equations ##Q_{net}=Q_1+Q2## The Attempt at a Solution ##Q_{net}=Q_1+Q2## ##-15 = +5 + Q_2## ##Q_2=-15-5 = -20nC##

If an electron starts from rest 85.0 cm from a negative fixed source charge of -0.135 micro coulombs we use the equation ke final - ke intial + pe final - pe intial. In solving you use ke = pe which appears to cancel out the inital kinetic and potential energy but how can the initial potential...

Homework Statement Consider a conducting sphere with radius ##R## connected to a voltage source of ##V_0## volts. If the sphere is then covered by a dielectric spherical layer of radius ##9R## calculated the relative permitivitty ##\varepsilon_0## needed so that the field in the empty zone...

Please refer to the image attached. So, my doubt is: While calculating dW in the derivation, we know this work is being done by external force, because only then the unit positive charge can be made to move towards the charge +Q. So dW should be equal to Fext.dx but here in the book it is shown...

Quick question for you experienced "older people" :wink: (sorry, I couldn't word it in any better way - I think of it as a compliment of sorts in terms of acquired wisdom over me!): i.) What I mean is, can two doctor's of the same specialization (pick any...say, dermatology) charged wildly...

Homework Statement Two infinitely large conducting plates with excess charge 2Q and 3Q are placed parallel to one another, and at a small distance from one another. How are the charges 2Q and 3Q distributed? You may assume that infinitely large sheets of charge produce electric fields that are...