Electricity and magnetism Definition and 210 Threads

(1) I previously learned that a constant magnetic field causes a force on any electrons within its range. Clearly, this force would cause electrons to move. Isn't this creating a current? (2) However, now apparently I am told that the only varying magnetic fields can create a current. I.e...

I am having difficulties writing my damped oscillations lab report. We were asked to write a short essay on eddy currents (creation,direction advantage and disadvantage) and their relationship with torsion pendulums. Also,we have to explain if the copper wheel in the torsion pendulum could be...

Homework Statement Using an electron as a point particle of charge −e inside a positively charged sphere of radius R ≈ 10^(−10) m and total charge +e, find the density ρ(r) of the positive charge for which the electron oscillates harmonically about the center of the sphere assuming that the...

I have found an equation which gives the EMF generated in a coil when a magnet is spun near it, the equation is given as: E = FNAω × 10-8 volts. Where F is the field of the sample perpendicular to the axis of roation, N is the number of turns, A is the effective area of the coil and ω is the...

Hello, I want to create a motion using electricity, using the cheapest means possible (DIY). Basically I'm trying to rotate an object 90degrees when the current is on, and back to its original position when the current is off. The questions are: 1) Is this possible? 2) Can this be done using...

I'm trying to understand how to calculate the strength of the magnetic field generated by a current loop. What I know so far is: When a current moves around a loop of wire it generates a magnetic field which looks a bit like that of a solenoid, only not so concentrated through the center of...

Is displacement current always equals to conduction current?if not then can anyone give me an example for it?if yes,then can anyone prove it?

1. Say that an electron is heading towards the Earth from the sun with an initial known velocity v. And we know that at Earth's surface the magnetic field is given by B1. This B varies as (R1/R2)^2 where R1 is the radius of the earth. How can I find the location in space, R3/R1, where R3 is the...

Hello, I'm working on a personal project that requires a very precise, but not very powerful, ping pong ball launcher. Would it be possible to coat a ball in metallic conductive paint, and then fire it from two rails like a railgun? Would I still get a constant net force in the correct...

I found two ways to solve this problem, but I get two different solutions, it's confusing because I can't see the flaw in wrong solution. 1. Homework Statement Long cylindrical inductor of diameter D1 and inductance L1 is connected to battery and creates magnetic field B1. Inductor is then...

When you take two magnets one being positive, the other negative. What is the chemical makeup of these two magnets that makes them repel each other. And if I have this correct, electricity is caused by magnet coils spinning around which generates electricity. What is it about magnets (especially...

Homework Statement A hypothetical magnetic field existing in a region is given by ##\vec{B}=B_o\vec{e}_r##, where ##\vec{e}_r## denotes the unit vector along the radial direction. A circular loop of radius a, carrying a current ##i##, is placed with its plane parallel to the X-Y plane and the...

Homework Statement I got questions a) and b), but I'm stuck at c) and d). Homework Equations Kirchhoff's Loop and Junction rules. Equivalent resistance in series: Req = R1 + R2 Equivalent resistance in parallel: Req = ((R1)-1 + (R2)-1)-1 The Attempt at a Solution I really haven't gotten...

Homework Statement A very large slab of material of thickness d lies perpendicularly to a uniform magnetic field \vec H_0 = \vec a_zH_0, where \vec a_z is the unit vector in the z-direction. Determine the magnetic field intensity (ignoring edge effect) in the slab: a) if the slab material...

I am in search of an electromagnet which has high magnetic remanence (or retentivity) even when the current through the electromagnet is zero. Can someone provide information about such a material?

There is something I am confused about when it comes to the force between two parallel wires carrying current, specifically why when they carry current in the same direction the wires are attracted to each other. I understand that when you use Flemming's left hand rule and consider the electrons...

Hello everyone. For this semester's laboratory, we are required to work on a project on the topic of E&M (preferably). They've given us freedom of choice as to what we want to work on and I was wondering if any of you guys know some interesting and cool topic we (me and my partner) can study...

Hi Everyone, I need to write an essay for my electromagnetism class and i was wondering if anyone has good topic ideas. My criteria is that it needs to be 10 pages and I would like something that is interesting for me to research and write about. I was thinking so far of magnetic levitation...

I'm a new TA in a physics laboratory and we're going to redesign experiences for fundamental physics II lab that is a semester course on electricity and magnetism for undergraduates in their 2nd year. What is your proposed list of experiences for a Physics II (Electricity and Magnetism)...

I don't understand what charge density is meant in the equation: div E = constant times charge density. I have the derivation in front of me and the last step follows from accepting that the rate of change of the integral of the field divergence per change in volume is the same as the rate of...

Can someone provide for me a proof that the total energy of my equivalent capacitor is equal to the sum of the energy in all capacitors? Or, if this is untrue, tell me why? Is this applicable to current and resistors too? Thanks a lot.

Hello everyone. I am searching for a book full of practice problems in Electricity and Magnetism and was hoping someone could recommend some. I have been searching on my own, but could not find any. I have a classmate who has one from china, where it is pure questions relating to the subject and...

Homework Statement A charged particle moves in a straight line through a particular region of space. Could there be a nonzero magnetic field in this region? In either case, include a sketch as well as prose in your justification. Homework Equations The Attempt at a Solution The...

Thirty years after learning E&M from the wonderful book by Purcell, I noticed that the copyright page of my dog-eared copy of the 1965 edition includes a notice stating that it is available for use by authors and publishers on a royalty-free basis after 1970. The book has gone through two more...

I am a computer science major and we are required to take two semesters of physics. First semester is based on mechanics and the second semester is focused on electricity and magnetism. I was wondering how these topics are used in computer science and in what specific area? I have tried looking...

Homework Statement A force eld E has the spherical components Er = (2Dcosθ)/r3 Eθ = (Dsinθ)/r3 E\phi = 0: (a) Evaluate by line integration the work it does in taking a point (parti- cle) from point A in the diagram to point B via the quarter circle r = a; 0 <...

Hello, I have started reading a beginners book (from the "stop faking it" series) on electricity and magnetism. Its supplied with funny little experiments to help me understand the topic. But I have trouble understanding the intimate relationship between electricity and magnetism. I believe I...

hey everyone, I have a questions, that is very general, and perhaps, silly... but why are coils so significant in terms of electricity and magnetic fields? why is it when you push a magnet through a coil, you get a charge, but not when you touch it to a straight copper pipe? Or when you see...

Can someone recommend a physics book on electricity and magnetism? The book that I just finished reading for my class was https://www.amazon.com/dp/0971313458/?tag=pfamazon01-20 The book above hardley mentioned vectors and I am looking for a book that explains all the concepts in terms of...

If a prerequisite for E&M is Multivariable calculus, why is it offered in high school (without that pre-req)? Is the High School E&M equivalent to physics 2 in college, and if that is so, Physics 2 is still offered before Multivariate calculus. Can someone clear this up for me. Am I getting two...

I wasn't really sure where to post this, but I am currently taking a second year Electricity and Magnetism course this term. I want to be able to do well in this course in order to keep my GPA up, but I don't have a particular interest in this class and the prof flies through the material at a...

Homework Statement please cheack my answears and see if they are right, please help me solve the wrong ones thankyou ! (1)if you were to expend 10 J of work to push a 1 C charge against an electric field , what would be its change of Voltage ? voltage = electric potential energy /...

Author: Edward Purcell Title: Electricity and Magnetism Amazon Link: https://www.amazon.com/dp/1107013607/?tag=pfamazon01-20 Prerequisities: Freshman mechanics. A year of calculus. Purcell introduces vector calculus from scratch, but most students who hadn't already had vector calc would...

Hey. So I switched from ChemE to Engineering-physics (I guess I followed my hearth here, instead of my head), and this entails I will have to take a course in Electricity and Magnetism this semester. During the previous one, the Engineering-physics guys took a course in mechanical physics, and...

Homework Statement I've been set an assignment and I'm struggling with one question in particular: Homework Equations 'Use the following data and plot the graphs for a point charge' 'Plot graph of E against r^2. Interpret the graph to describe electric field strength and electric...

What makes Electricity and Magnetism a "unified" force? I'm taking upper level Electromagnetism and we've dealt with the various formulas dealing with electricity and magnetism. It seems to me that we are still largely dealing with them separately. In that, I mean we have a thing called a...

Hello, Firstly i am new here ( not offering an excuse) and an on and off lurker to this awesome forum. I am trying my best to fit into the established rules ,sorry if i broke any inadvertently. If kinetic and potential energy represent the same things why are there entities representing the...

Since the instructor of my course doesn't use a textbook and just teaches based off his notes, what would be a good text to supplement my learning (when asked what he recomends, he just said find something in the library). Does electrodynamics = electricty and magnetism? I've heard this one is...

Hello PF, I am a few weeks from starting my second year as an undergraduate. This fall I will be taking the Electricity and Magnetism course for physics majors (crosslisted for graduate students). Last spring I took the introductory physics course on electrostatics and magnetostatics. The...

hi , i wanted to ask why does current in a wire produces a magnetic field ? and can anyone explain how maxwell related electricity and magnetism , easily (im in high school)

A 1000-turn toroidal solenoid has a central radius of 4.2 cm and is carrying a current of 1.7 A. What is the magnitude of the magnetic field inside the solenoid at the central radius? (μ0=4∏×10^-7 T ∙ m/A) r= 4.2cm= 0.042m B=(μ0)(I)/(2∏)(r) ⇔ (4∏×10^-7)(1.7)/(2∏)(0.042) ⇔ 1.43x10^-8 T? Or...

If the area of a tube is 0.0000283 m, with moving ions contributing to a magnetic field of 44.0x10^-4 T. What is the current flowing through the tube? [permeability of free space 'mu subzero'= 4∏x10^-4]. I don't have a clue of how to start attacking this problem, have a genius professor, but...

No, you didn't read the title wrong. I am really self studying a physics class. I just finished Mechanics (Physics I) and since I want to go to college to study physics to become an engineer or physicist. I need to take the next class, E&M (Physics II, Electricity and Magnetism). However, I...

I have 2 questions. I have been thinking about these two things a while, and got no one to ask, so hope to get some info/answeres here:) 1: When an electron is standing still, it produces an electric field (and no magnetic field), right? So when many electrons is moving with a constant...

I have just created a short animated video explaining all the concepts of electromagnetism. It is at: http://youtu.be/XiHVe8U5PhU I put a lot of of time and effort into making the animations, so please take a look at this, and please pass it along to anyone who you think might be...

My question is how do I find the voltage across a capacitor? I have an RLC circuit with a switch and battery. It only gives me the values for the battery, L, C, and R. My main question is, is there an equation or something to find the voltage across a capacitor?

I am a biochemistry major and I need to take the first two introductory physics courses as a prerequisite to physical chemistry. I can take regular pchem, which requires calculus based physics or pchem for biochemists, which only requires the algebra based physics. With the way my university...

Homework Statement Four point charges have equal magnitudes. three are positive and one is negative, as the diagram shows. they are fixed in place on the same straight line, and adjacent charges are equally separated by a distance d. consider the net electrostatic force acting on each...

I'm currently in an electricity and magnetism physics course and we're using the 8th edition of Serway. I'm looking for a review type book that focuses on problem solving with examples and explanations rather than theory. Here are the topics we are covering throughout the course: 23...