Solenoid Definition and 705 Threads

I got into a little debate about the nature of a problem where you put a giant solenoid around the equator of Mars to give it a magnetic field (not my idea, I like futuristic things but... there are probably better things to worry about). Anyways, I got into a debate about the effect of the...

Homework Statement Example 5.9 in Griffiths's Introduction to Electrodynamics 4th shows us how to find B of a very long solenoid, consisting of n closely wound turns per unit length on a cylinder of radius R, each carrying a steady current I. In the solution, he goes on to explain why we don't...

I'm trying to use a solenoid to measure the magnetocaloric effect of dysprosium. The effect is highest at the Neel temp which is down near 180K. I have a solenoid in a cryostat to get the correct temperature. The cryostat's heat exchanger is made of a thick copper cylinder and I think it is...

I'm making a solenoid electromagnet for gcse demonstration purposes and I'm trying to get a strong:muscle:, clear magnetic effect. I'v wrapped about 100 turns of enamel plated copper wire around a 4" bolt and also a 4" ferrite rod, and am applying 9v DC from a pp3 battery cell. In both cases...

Hello, I have seen that biot savart's law works for infinitely narrow wires: "The formulations given above work well when the current can be approximated as running through an infinitely-narrow wire." When I wanted to derive the magnetic field of a solenoid, I had to do this substitution...

Homework Statement [/B] A solenoid is not connected to an ideal voltage source. Its radius is 0.05m, it has 800 loops per meter and its resistance is 0.2Ω. ε=120V. Around the solenoid we bind two loops of a wire. The loops are attached to a resistor with the resistance of 0.8Ω. Suddenly, we...

I don't understand something. At the center of N circular loops, the magnetic field is μ_0NI/2a. And that for a solenoid is μ_0nI. Why are they not the same when the number of loops is large and the length for the solenoid is long?

Hi guys, a solenoid coil 10x4 mm needs to be moved along the vertical axis of a strong magnetic field (up to 14 Tesla) generated by a superconducting magnet. The coil must be contained into a classical probe for NMR spectroscopy, and moved vertically inside that probe. The main issue I am facing...

Good day , i have an issue with the derivation of the mutual inductance of coil inside solenoid formula I1 is an alternating current which means that B is varying, and we know that the Flux 21 is equal to the integral of the dot product of B and A2 but as B is varying we CAN NOT take it out...

Homework Statement [/B] A conducting coil of radius R is outside a long solenoid with a cross section of radius r. What is the emf induced in the coil? Most example problems of this type I think are solved based on Faraday’s Law. These examples do not use the distance from the solenoid to the...

Hi I have attached a picture here, of a solenoid with a copper block connected to a battery suspended in it. The current moving is clockwise, So the magnetic poles would be as shown. Now my problem always is this, I get so confused with this, I used Fleming's left hand rule to find the...

Homework Statement A solenoid of volume V, current I and n turns per unit length has an LIH core, relative permitivity is \mu_r. This core is then slid out so that a fraction f of the solenoid's length is filled with air/vacuum (and 1-f is filled with the core). Neglecting hysteresis, what...

Hi!, I have a question for you geniuses (geniusi?) Why are there two different equations to find the magnetic field of a solenoid and a coil with multiple turns? (According to my textbook) The equations for each are Solenoid: Coil with multiple turns: Why are they different? Is there a...

Hi everyone, Lately I have been studying the Poynting Flux and I am familiar with the classic examples of how it can be used to describe the power being dissipated by a resistor and the energy flowing into a capacitor, but I have never come across a similar analog for how the Poynting flux...

Homework Statement [/B] I am working on a lab report regarding the creation of an electromagnet using an iron core solenoid (just a nail wrapped with copper insulated wire). Before continuing with the creation of the electromagnet, I had to answer some questions regarding my knowledge of...

In my experiment, I intended to find out how the change in the bar magnet drop height from solenoid affected the emf induced in the solenoid, however, I am unable to come up with an equation that shows a relationship between the two variables. I have thought of Biot-Savart law, but I do not...

In a solenoid of N loops and uniform magnetic field B, the magnetic flux is B*N*A, where A represents the area surrounded by each loop. I see that the N comes from the fact that you have one A for each turn, and you have N turns, so the total "area" is NA, but why do we use this? Why isn't...

Homework Statement I have a solenoid with a wire carrying current in the center. The wire has a radius of a, the solenoid has a radius of b. I need to find the magnetic field inside of each region. Inside of the wire, mu =/= muo. Homework Equations Wire B field = uo I/2*pi*r Solenoid B field...

Does the initial position of the plunger in the solenoid make a difference to the pull force it is subjected to? I mean in the default position how much % length of the plunger should be within the solenoid so that optimum force is delivered to the plunger when the solenoid is turned on? I see...

Will placing a solenoid inside another solenoid increase it's over all strength? While doing research into solenoids I came across the MagLab (The National High Magnetic Field Laboratory) where they place coils one inside another to bolster the field, and reach upwards of 45 Tesla. They use an...

I am looking to make a pencil whose tip moves to create a waveform as you move it across the paper.In essence, I want to be able to record a sound and then play the sound through the pencil whilst I draw with it, of course, I will use software to lower the frequency to make it more of a waveform...

Hi, I'm wondering if a solenoid is only hot by copper resistance or in addition with the inductance produced into the coil too ? Another small question : in the sofware Femm there is a computing result parameter called "voltage drop"; does it means you need ( at least ) x volt to get the...

Homework Statement Decide the direction of Magnetic field of a very long solenoid consisting of n turns per unit length on a cylinder with current I flowing through. Homework EquationsThe Attempt at a Solution Deciding direction of the magnetic field: Considering cylindrical coordinates with...

If I do the x-axis rotation for a solenoid, how will the magnetic field change? Would it also rotate along x axis?

Please help me understand. Attached is a pic of some quick calculations My solenoids self inductance is 0.145mH. The coil is 117 grams of copper. I calculated with 300 amps on the picture but I only put 170A through it the other day. I had it hooked up for 2 seconds touching it at the same time...

Hello all. Me and some friends are building a coil cannon, and we've been doing some calculations [I know its unecessary but... well, we're physicists! (well, physics students...)]. But we got stuck. How to calculate the force acting on a steel bar (or some other ferromagnetic material, maybe...

Homework Statement Part d of attached question Homework Equations Solenoid equations B=uo n i The Attempt at a Solution B (absence)=B (presence) Uo n (i+im)=u n i im=798A But answer is 794A.[/B]

Hi - I am designing a circuit with two solenoids (12 V, 1 Amp each) in parallel in order to get power of two upon activation using an arduino. I am able to wire one solenoid using 12 V adapter rated 3 Amp, 1 TIP120 darlington transistor, 1N004 diode and Arduino connected to base of the...

Hi, I have a problem with the fomular u=m·B and u=B^2/4pi Since I want to calculate how many magnetic energy on a solenoid, I couldn't decide which fomular should I use.

Homework Statement Homework Equations B = μ Ni/l The Attempt at a Solution Question no. a:[/B] And Q no. b: I am not sure about the step in the red circle in the first figure, and my book doesn't give a solution, so what is your opinion?

I'm trying to come up with a lightweight solenoid linear actuator, by constructing two electromagnets that telescope. The outer coil would be wrapped around a soda straw, and the inner coil would fit inside the soda straw and be wrapped around something smaller, like a bamboo skewer (which also...

Hi, I was wondering whether a bar magnet would induce a current if it was moving external to the solenoid, rather than within the coil. I see no reason why it wouldn't occur, but I've never seen it displayed or mentioned so I'm not sure. Thank you.

Hello. Me and my friends planned to make a solenoid. We used 22 gauge insulated wire and we used an old laptop charger (19v 3.3A) as the power supply. Earlier we used a power supply of 1A and it wasn't enough. When we connected everything and switched on,we saw the solenoid behaving weirdly . We...

I am trying to calculate the forces (in Newtons) between a permanent magnet, and an electromagnet. All I can find is interactions between permanent magnets, electromagnets, but never both and it is getting really confusing for me to do the calculations. So basically, if I have a permanent...

Homework Statement Homework EquationsThe Attempt at a Solution These are problem 5.1 (b) and the solution. I understood the gap between each loop is 1/N, but why does each loop have vertical direction current amount of I/N ?? [/B]

Homework Statement A 470-turn solenoid having a length of 25cm and a diameter of 10cm carries current of 0.29A. Calculate the magnitude of the magnetic field inside the solenoid. Homework Equations ##B=μ_0nI## where ##n=\frac N L##...

Hey ! Let's say I have a solenoid that is only half-filled with a magnetic core. Now I want to know what is the loss due to Eddy currents. First, I want to find the magnetic field with Ampere's law. With this kind of geometry, I'm not even able to apply Ampere's Law ! have of picture here of the...

Homework Statement Consider a cylindrical solenoid(of radius a,and length h>>a,having n turns of wire for unity of lenght),The solenoid is connected to a resistance R and,at instant t=0 a current i(0)=i0 is flowing in the wire.Prove that poynting's theorem is verified for t>0[/B]Homework...

Trying to understand solenoids and magnets a little better but have some questions Solenoids usually create magnetic fields when a current runs through them. Also the direction of the current determines how the magnetic field lines direction. Also the solenoid, similar to a magnet will then have...

EDIT: While going over the data again I noticed the sensor was giving us the data in µT, I'm editing the data I wrote to reflect this change of x10^-3 in magnitude. 1. Homework Statement On lab class we are exploring the relation of a magnetic field on a solenoid (B) with its number of turns...

Hi, I'd like to build a homopolar generator. Since generating magnetic fields of uniform density of any useful size is very tricky to do with off the shelf permanent magnets (I've tried!) I had the idea to use DC solenoids instead. But with a rotating helical plate in place of the cylindrical...

Hello everyone! I am new to these forums and glad to see a great community helping out each other. I have a question regarding a solenoid valve design. What should be the design ethics and safety considerations for a 240 volts AC connected solenoid valve that is used for a cryogenic vessel...

Homework Statement The magnetic field in the middle of a solenoid of length L= 40cm and area of the cross-section A=12 cm^2 is B = 3 mT. The current through the solenoid is I = 4 A. What is the number of turns in this solenoid? Homework Equations BL=μ0*n*I =(4πx10^-7)*n*I The Attempt at...

Hello everyone, So for a personal project I want to calculate the force necessary for a solenoid (electromagnetic coil) to keep a permanent magnet triangle locked diagonally up and down at the same time so that it does not move in any direction. I need to know the values for coil thickness...

Hi, I want to find an equation for the force generated by a solenoid on a moving steel ball bearing given current, number of loops, area of the solenoid for a lab project. I've tried looking through many sources, but was unable to find anything. I also tried looking at this previous discussion...

Hi all, I need help in understand what happen when a coil, let's say a solenoid with N turn (N = 1 or whatever) produces a very high magnetic field. I know that the solenoid could explode, this means that there are forces on it, and I don't know how to calculate. Can somebode helps me? Can you...

Hello. I know you can calculate the magnetic flux density (B) outside a solenoid using Biot-Savart law, but the law uses the magnetic vacuum permeability. Suppose that I placed an iron core in the solenoid, but not outside it. How does B outside change? And now suppose that I place a piece of...

Homework Statement [/B] N=600 (number of loops) a1=200mm a2=240mm h=40mm δ=1,5mm or l0 S0=1,1*S (Cross sectional area) B0=1,2T I need to find energy of toroid and currect going through it. Solution: W=4,08J, I=6,44A 2. The attempt at a solution So far I managed to calculate S and S0...

since graphite conducts. if spiral shape is drawn with pencil on the wall (thick , dark lines) will a voltage difference appear between inner and outer end of the spiral when a varying magnetic field is switched on, normal to wall