Electrcity Definition and 96 Threads

Maxwell equation in absence of charges and currents are $$\nabla \cdot \bf{E} = 0 \\ \nabla\cdot B=0 \\ \nabla \times E=-\frac{\partial B}{\partial t} \\\nabla \times B=\mu \epsilon \frac{\partial E}{\partial t}$$ Wave equation is $$\nabla ^2 \bf{E}=\mu \epsilon \frac{\partial^2...

Homework Statement Two +3.0nC charges are shown in the diagram below which are spaced 10cm apart. What are the strength and direction of the electric field at the position indicated by the dot in the figure (Figure 1) ? What is the electric field in N/C? What is the direction of the electric...

Homework Statement We have an ammeter with 20Ω resistance and a range of 10mA or 0.01A. The different ranges are 3000mA, 300mA, 30mA. Calculate the shunt resistors a, b and c. Homework Equations The Attempt at a Solution Ia = 0.01A ; Ra = 20Ω ; I = 0.03A Ua = Ia ⋅ Ra = 0.01A ⋅ 20Ω =...

Homework Statement A capacitor is made of two parallel plates of area A, separation d. It is being charged by an AC source. Show that the displacement current inside the capacitor is the same as the conduction current. Homework Equations Idisp = ε(dΦE/dt) Q = CV C = Aε/d Xc = 1/(2πƒC) Q(t)...

Homework Statement Homework Equations V = IR P = IV The Attempt at a Solution The attempt is much too long to type out, so here is a link to a picture of my work. I'm mostly concerned about part C, because I've seen some similar problems and my answer has been different by a magnitude of 10...

Hello everybody! I am excited to be part of this forum. It's the first time for me. I am 41, from France and with my sons (9, 7 and 6) we love physics. I have studied economics and discovered my interest for physics only a few years ago. I try to learn things by myself with videos from You tube...

Knowing that Gauss' law states that the closed integral of e * dA = q(enclosed)/e naut, how would you find exactly what A is in any given problem? I know it varies from situation to situation depending on the geometry of the charge. For instance, I know that for an infinite wire/line of...

So in a graph where V is a function of x, when the slope is negative what does that mean about the direction of the field along the x axis? What about when the slope is positive?

I am working on "electrical energy" storage and I want to know why exactly can't we store "electricity" from a power plant. My understanding is that "electrical energy" storage actually refers to the conversion of electricity to other forms of potential energy (such as mechanical eg: dam, or...

Hello, does anybody know if there is a connection between the voltage (work) for the bandgap of a diode, the temperature voltage and the flux voltage?

Homework Statement A battery with = 12.0 V and internal resistance r = 1.0 Ω is connected to two 6.9 kΩ resistors in series. An ammeter of internal resistance 0.50 Ω measures the current, and at the same time a voltmeter with internal resistance 10.0 kΩ measures the voltage across one of the...

Hi, While studying the coaxial cable, i noticed that the magnetic field of the inner conductor can pass through the hollow conductor (can be calculated in the region 3). However, the boundary condition of the magnetic field at the surface (between dielectric and perfect conductor) of a perfect...

I am trying to measure the charge(or voltage) of a positively charged sphere by touching it with a non- calibrated electroscope. I am getting consistent results in the separation(or angle) between the metal leaves, but I don´t know how to calculate the voltage between the leaves from there. I...

So what's the smplest illustration for voltage ,current and resistance and what's ohms law ?

Homework Statement Consider the system shown to the right. Particles 1 and 2 are fixed in place while particle three is placed at the location shown and released. Let’s look at the mechanics of q3, which has a mass of 3.00 X 10-5 kg. What will be the net force on q3?What will be q3’s...

Homework Statement Homework EquationsHEAT PRODUCED=WORK DONE BY BATTERIES - ENERGY ABSORBED BY CAPACITORS The Attempt at a Solution INITIALLY BEFORE SWITCH CLOSED :Initially a current flows only in the left most loop involving 4 microfarad capacitor.The charged on the capacitor during...

The main question stems from the answer for this one: If I have a light year long rod and push it on one end, how long would it take for the other end to move? Still Unsure of this answer. Main Question: If I had 2, light-year long conductive rods with a voltmeter attached at the ends then...

If your axel in you car was magnetic with copper wire casing would that produce electricity? If so how much? If there is no resistance in that process then there wouldn't be a detrimental effect on the performance (bar added weight of the wire) With the raising popularity of electric cars it...

I'm doing independent study on semiconductors to prepare for a future class and I'm having problems with some problems that concern finding the n and p of doped Silicon given only a temperature, NA, ND, and Ni. I understand that n*p=Ni^2, but, given that this means that n does not equal ND (and...

Homework Statement Homework Equations 1/Rt = 1/R1 + 1/R2 + ... The Attempt at a Solution I can do part (i) okay. It is simply 1/12 + 1/12 = 1/6, so R = 6. But I have been trying for ages to figure out part (ii). I tried re-drawing the circuit in different forms but it didn't help me...

Homework Statement Ammeter shows 1.2 A and 1.0 A. How large amount of charge passing through the lamp in 1 minute? https://physicsforums-bernhardtmediall.netdna-ssl.com/data/attachments/84/84982-6e293679b3592fb475f0f9cac697526f.jpg Homework Equations Q=I*t[/B] The Attempt at a Solution I =...

Homework Statement The overall resistance of the circuit is 12.5Ω. Calculate the value of the resistor labelled R in the circuit. Homework Equations 1/R = 1/R1 + 1/R2 R = V/I The Attempt at a Solution I understand that you use the first equation for parallel resistors and the second to...

I need this clarified. I've been told that if you have a circuit with a load resistance of 0, but you have a power supply of internal resistance, when you have no voltage coming from the power pack you will still get a current. I don't understand how this works. I've been told its because the...

In an RLC series circuit let applied EMF be given ##V=V_0\sin\omega t##, $$Z=Z_C+Z_R+Z_L=R+i\left(\frac{1}{\omega C}-\omega L\right)$$ $$|Z|=\sqrt{R^2+\left(\frac{1}{\omega C}-\omega L\right)^2}$$ Then $$i(t)=\frac{V(t)}{Z}=\frac{V_0e^{i\omega t}}{R+i\left(\frac{1}{\omega C}-\omega L\right)}$$...

Homework Statement Hey everyone I have a physics e&m question: [/B] http://blob:https%3A//www.physicsforums.com/aa779f37-be23-43d7-a888-d70263a3854b Homework EquationsThe Attempt at a Solution I took the derivative to find the magnitude of the induced voltage. (do I need to add a constant...

I got a question towards kinetic energy and elektrical energy. They always talk about about particle accelerators or devices when talking about transformation of elektrical energy into kinetic energy of elektrons. But do elektrons also have kinetic energy when they are circulating in an...

I have read about Japan's solar power plant in space. Would it not be easier to build a plant similar to the huge circular spinning space stations you see in movies that create their own gravity/downward force? Once something that large is spinning in space could you not use the motion to...

Homework Statement [/B] In a thin rectangular metallic strip a constant current I flows along the positive x-direction, as shown in the figure. The length, width and thickness of the strip are l,w and d, respectively. A uniform magnetic field B is applied on the strip along the positive...

We have a solar tracking device that uses phase change of paraffin wax when heated inside a solar receiver. With a helical slot in a torque tube we can translate the expansion into rotational motion. We use this rotation to point solar panels at the sun, thus generating more electricity. Look...

Homework Statement This is problem 3.4 from Prucell and Morin if you have the book. Homework Equations None The Attempt at a Solution Electric field inside a conducting sphere is zero. Let P be a point on one of its equatorial plane. The field along the plane is zero. So I know the charge...

Homework Statement Trying to come up with an equation of V_D in terms R_S, R_d, R_D, V_i, G G is a constant Homework Equations Sum of voltages around a loop = 0 Sum of currents at a node = 0 Voltage divider Current divider Resistance of resistors in parallel The Attempt at a Solution...

A 5μF capacitor is connected in parallel with a 2MΩ resistor and the combination is then connected in series with a 1MΩ resistor through a switch to a 12V battery. Find the time taken for the voltage across the capacitor to rise from zero initial value to 2V after the switch is closed.From what...

i have studied that a conductor is equipotential and charges don't flow through it but how does it flow through a wire?

I'm a high school physics student. I want to do an experiment to see what happens when a high frequency alternating current goes through a magnet. To create the high frequency alternating current could a photo resistor do that for me? Does the photo-resistor create an alternating current with a...

Homework Statement Find the equivalent resistance between AB. Homework EquationsThe Attempt at a Solution I could not find any Wheatstone bridge or series parallel combination. Should I use star delta transformation ? If yes, how exactly should I use it ?

Homework Statement Find the potential difference ##V_A– V_B## for the circuit shown in the figure. Homework Equations Kirchhoff's laws. The Attempt at a Solution If we assign potentials to junctions starting by setting ##A=0## Current ##i_1## flow through each vertical resistances and ##i_2...

The formula to find the total resistance in a parallel circuit is 1/R=1/R1+1/R2+1/R3, but wouldn't it be easier to use R=1/(1/R1+1/R2+1/R3)? I've only ever seen the equation written like that once before, and I'm wondering if there's a reason as to why it's never really used?

I was told that for resistors connected in series (whatever the equivalent resistance be) the current flowing through a circuit will be a constant Say i had 'n' number of resistors in series connected to say a battery such that the equivalent resistance was equal to that of an insulator, would i...

There is a frame that circles around a point because of the Lorentz force. Frame is placed between North and South magnets and there is s current flowing in a frame. My question is - can a charge in a wire move in a circle - for instance clockwise? I mean, if the square frame turns, then the...

Hello enlighted people of this forum. I'm an undergraduate from a university in Colombia, my subject of study is software engineering but I have a class which is named "Physics 2", this class introduces the subjects of simple harmonic motion(pendulum, sound waves, etc), electric fields, Gauss's...

Homework Statement An inductor with value L and a capacitor with value C are connected in series to a power source. At time t, the voltage of the power source (i.e. the voltage across both the inductor and capacitor) is given by ## v(t)=Asin(\frac{2t}{\sqrt{LC}}) ##. If the voltage across the...

Homework Statement A neutral atom is known to have a nucleus with a positive charge of 2.4 x10-12 C. How many electrons does the atom have? Homework Equations q=Ne The Attempt at a Solution None

magnetism and electrcity! according to me as i think that when an electric field is created by creating a potential difference ,the force from the electric field changes the direction of spin maybe due to which the opposite effects takes place from magnetic field because magneticdipole becomes...

I love to know how electricity is usefuel for us, electric cars, lighting and refrigeration, i love physics but i also like to know what the universe is made of, how is that a bunch of cells and we think! dam! i love chemistry. I also like solar panels and would like to really know how they...

Why is Robotics and Mechatronics in Mechanical Engineering if its more electrcity!? Doesent Robots and Mechatronics have to do more with Electrcial Engineering? Robots think with electronics not with mechanical or thermodynamics.

Hey everyone. I'm taking physics 2 right now in the summer and my professor keeps saying you can get free electricity, but doesn't tell us how. He's pretty stuck up and has been saying this since class started 3 weeks ago. It's really annoying and as a class we want him to shut up. Well, that's...