What is Solenoid: Definition and 743 Discussions

A solenoid (, from the Greek σωληνοειδής sōlēnoeidḗs, "pipe-shaped") is a type of electromagnet, the purpose of which is to generate a controlled magnetic field through a coil wound into a tightly packed helix. The coil can be arranged to produce a uniform magnetic field in a volume of space when an electric current is passed through it. The term solenoid was coined in 1823 by André-Marie Ampère to designate a helical coil.In the study of electromagnetism, a solenoid is a coil whose length is substantially greater than its diameter. The helical coil of a solenoid does not necessarily need to revolve around a straight-line axis; for example, William Sturgeon's electromagnet of 1824 consisted of a solenoid bent into a horseshoe shape.
In engineering, the term may also refer to a variety of transducer devices that convert energy into linear motion. In simple terms, a solenoid converts electrical energy into mechanical work. The term is also often used to refer to a solenoid valve, an integrated device containing an electromechanical solenoid which actuates either a pneumatic or hydraulic valve, or a solenoid switch, which is a specific type of relay that internally uses an electromechanical solenoid to operate an electrical switch; for example, an automobile starter solenoid or linear solenoid. Solenoid bolts, a type of electromechanical locking mechanism, also exist. In electromagnetic technology, a solenoid is an actuator assembly with a sliding ferromagnetic plunger inside the coil. Without power, the plunger extends for part of its length outside the coil; applying power pulls the plunger into the coil. Electromagnets with fixed cores are not considered solenoids.
The term solenoid also refers to any device that converts electrical energy to mechanical energy using a solenoid. The device creates a magnetic field from electric current, and uses the magnetic field to create linear motion.

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  1. fisher garry

    Magnetic field inside a solenoid

    I have a problem with the derivation above I don't get how Can someone derive this and illustrate this visually for example by using Figure 2 or using another drawing?
  2. Indula

    How to calculate the inductance of a center tapped solenoid ?

    I'm trying to drive a transformer using a ZVS power supply. The primary coil that we use here has to be wound center tapped. The output frequency depends on the inductance of the primary winding and capacitance used in the circuit. The circuit of a ZVS power supply is as follows, The...
  3. M

    What is the Relative Permeability of Iron in a Solenoid?

    So the equation is L=μoμrN^2A/l I am wanting to make μr the subject and I think this is how i do it? μr = L*l/μoN^2A However when I type in this equation i am expecting to get about 200 for the relative permeability of iron. However, i am getting like 9x10-3 which is nowhere near 200. For...
  4. Adesh

    I Calculating EMF in a Solenoid: Understanding the Relationship of Turns and EMF

    If I have a solenoid with N number of turns in total. And if I say that in each turn the EMF is equal to e then can I conclude that the total EMF in the solenoid i.e. from A to B is N \times e . I’m asking this because whenever a current I flows in each turn of the solenoid then we...
  5. patrykh18

    Magnetic field outside a solenoid

    In his book on electrodynamics, Griffith talks about the magnetic field outside a solenoid. Firstly instead of dealing with a typical solenoid with closely wound loops, he instead works with a cylinder with a surface current that has no z-component. To get the angular component of the B-field...
  6. D

    How to find the magnetic field and magnetic force due to a solenoid loop

    I'm not so sure how to begin with this problem. I was thinking of usign superposition. I think that the field on the conductor due to the parallel segments of the coil is zero, since Ampere's Law tells us that the field outside the solenoid is zero, right? For the perpendicular segments, I used...
  7. C

    Combine 3 Eqns for Plasma in a Solenoid

    ∇p=j×B (eq. 1) K=nI BSolenoid=μnI⇒μK (eq. 2) ∇p=-2p0r/(a2) (eq. 3) Combining these three equations: j=-2p0r/(a2μK) (θ hat direction) Feel like this is too simple and might be missing a step any help would be much appreciated!
  8. Kartoshka123

    Zeeman effect: Experimental Setup and Explanation

    Homework Statement: Hello, I have to explain using numbers the Zeeman effect for hydrogen and the setup needed. I have done some research and if I'm not wrong, then a magnetic field of 1 Tesla is needed. I have no idea how to achieve that using commercially available products and how to even...
  9. N

    What are the advantages of a solenoid motor over an electric motor?

    Can force produced by solenoid be converted to mechanical force and be more efficient than electric motor's force?
  10. C

    Induced Current In a Tilted Square Inside and Outside a Solenoid

    Plot for the ring ^ Calculations for the Square ^ Plot for square without cosg on the outside calc ^ Plot for square with cosg on the outside calc ^ As can be seen the formulas for the square conductor do not connect at R, which I'm not sure if they should or if they should not as in this...
  11. P

    Circular loop of wire is concentric with a solenoid

    Question: In Figure (a), a circular loop of wire is concentric with a solenoid and lies in a plane perpendicular to the solenoid's central axis.The loop has radius 6.13 cm. The solenoid has radius 2.07 cm, consists of 8230 turns/m, and has a current i_sol varying with time t as given in Figure...
  12. C

    EMF induced in an off-axis solenoid due to a rotating magnet

    The red arrows correspond to the areas the solenoid will be moved too
  13. A

    Solenoid Lift Force Results -- Need Data Analysis

    Good Day, I am trying to pick up small ferro (Neodynium)) magnets vertically with a solenoid. I want to know how much magnetic force the solenoid can pick up. The formula I tested and actual numbers for my solenoid are in the image below. I know that the magnetic field of a solenoid is given...
  14. T

    Conditions needed for magnetic force on a conductor

    none
  15. T

    Inductance of a Solenoid with a Core inside

    For finding magnetic field ##B##, We see this question like two Solenoids. for the first one, we have ##\int B ds = \mu I## so ##B x_0 = \mu I n x_0 ## so ##B = \mu n I##. For the second one we have ##B = \mu_0 n I##. For the Inductance we have ##L = \mu l n^2 A## so we have ##L_1 = \mu x_0...
  16. K

    Strength of magnetic field at the end of a wire wrapped nail.

    V=I*R 6v=I*(0.6+0.9)ohms I=4amp B=100*(uo)(2N)(I)/L * 1/2 I think since the wire is double wrapped, we multiply the equation by 2, but since we are looking for the magnetic field at the end of the wire we also have to multiply the equation by 1/2 I=4A, uo= 4pi*10^-7 2N/L turns per unit...
  17. Abo

    Time constant of a Toroidal Solenoid

    Is my solution reasonable? What I got from my first attempt is that the time constant won't change. WHY? Because when we double the number of loops (N) we're going to have new values for both the self inductance and the resistance of the solenoid and so the ratio (L/R) stays the same. Here is a...
  18. B

    Biot Savart Law with Different Magnetic Permeabilities

    I would like to make a program that produces a 2D heat map showing the magnitude of the magnetic field produced by a finite length solenoid. The heat map would show the field strength along the radial and axial directions of the solenoid. I plan to divide the conductor into "infinitessimally"...
  19. diegbarrientos

    Influence of Core Change on Current in Solenoid Loops

    How does changing the core of the solenoid affect the current induced in the loop?
  20. Rayanna

    Self induction of a solenoid

    Two coils are made of copper wires of same length .In the first coil number of turns is 3n and radius is r . In the second coil number of turns is n and radius is 3r the ratio of self inductances of the coil is: I know that self inductance of a solenoid is μN2A/l ; where A = area of cross...
  21. C

    Effect of cross section shape of an iron core in a solenoid?

    I know the basic equations of a solenoid carrying a current, the consequences of having an iron core inside one, and how that derives from Ampere's law. But these suggest that the only figure of merit is the cross section area of an iron core and the solenoid, not their shape. Thinking in more...
  22. C

    Calculating Induced EMF in a Larger Solenoid Slipped Over Another Solenoid

    1. Problem statement A very long straight solenoid has a diameter of 3cm, 40 turns per cm, and a current of .275 A. A second solenoid is with larger diameter is slipped over it with N turns per cm, and the current is ramped down to zero over 0.2 s. a) What is the emf induced in the second...
  23. PainterGuy

    B Do the fields extend to infinity in a solenoid and for a wire?

    Hi, I wanted to clarify a point about the magnetic fields of a solenoid and wire. Do the fields extend to infinity? In my opinion, they don't but they can assuming the current also goes to infinity. They don't extend to infinity for a limited amount of current because they need to follow a...
  24. marino

    Power generated by a coil rotating in magnetic field

    The problem: a coil of radius r, length l and N turns, rotating with constant angular velocity ω around an axis perpendicular to its simmetric axis and passing for the center of the coil. The coils is submersed in a static magnetic field, intensity B0, perpendicular to the axis of rotation of...
  25. Spinnor

    B field of 1/2 infinite solenoid, equivalent current confguration

    I have wondered if there is a symmetric current configuration that gives the magnetic field of a half-infinite solenoid. With some thought I think I came up with such a configuration of current loops that produces the same magnetic field as a half-infinite solenoid Suppose we have a large but...
  26. Limddong

    Magnetic field inside a solenoid calculated with Ampere's law

    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. :)
  27. D

    Ratio of Inductance between 2 Solenoids?

    Homework Statement [/B] 1. Two solenoids, A and B, are wound using equal lengths of the same kind of wire. The length of the axis of each solenoid is large compared with its diameter. The axial length of A is twice as large as that of B, and A has twice as many turns as B. What is the...
  28. digogalvao

    Slowly oscillating surface current on a solenoid

    Homework Statement From an original surface current ##\vec{K}=K\hat{\phi}## on a finite solenoid, I got ##\vec{B}=\mu_{0}Kf(z)\hat{k}##, for ##r<R##. Assuming that ##\vec{K}## now slowly oscillates in time such as: ##\vec{K(t)}=K_{0}\cos\left(\omega t\right)\hat{\phi}##, so that I still can use...
  29. prodo123

    Magnetization of the core of a long solenoid

    Homework Statement A long solenoid of 60 turns/cm carries a current of 0.15 A. It wraps a steel core with relative permeability ##\mu_r=5200##. Find the magnitude of the magnetization of the core. Homework Equations ##N=\lambda L## ##\chi = \mu_r-1## ##\mu = \mu_r\mu_0##...
  30. shahbaznihal

    Total magnetic flux of a solenoid

    There is a solenoid of a certain radius, carrying a certain current. I draw an amperian loop of radius greater than the radius of the solenoid. If I calculate the total flux through this loop it should be, 1) Non zero for an ideal solenoid (where the field outside the core of the solenoid is...
  31. A

    I Where Can I Find a High-Turn Solenoid for Low Current and Strong Magnetic Field?

    Hi everyone, I am doing a project where I need a device with a strong magnetic field but low current. It also needs a simple relationship with the current. Solenoids and toriods are the best I can think of to use. However, because I want to keep the current low, I want to keep a high magnetic...
  32. J

    What does self induction per unit length signify?

    Homework Statement Homework EquationsThe Attempt at a Solution Self inductance L = μ0n2πr2l . This means it depends only on geometrical factors . So , self inductance in both the cases should be equal . But if I think in terms of L = Φ/I , then Magnetic field at the center is twice that...
  33. J

    Magnetic field due to a solenoid

    Homework Statement Homework EquationsThe Attempt at a Solution I am having trouble interpreting the language of the problem statement . What does it mean that "half number of turns are wound " ? When the solenoid is cut , the length becomes 1/4th of the original and number of turns also...
  34. F

    EMF induced in a coil encircling an ideal solenoid

    Homework Statement A current I(t)= (0,160 A s^{-3}) t^3 flows through an ideal solenoid with a turns density n = 9,00 \cdot 10^{-3} m^{-1} and a cross sectional area A_s=2,00\cdot 10^{-4} m^2 A single loop of wire has the same axis as the solenoid, but its radius is larger. That is: the loop...
  35. H

    Electric Force on a Charge in a Solenoid

    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...
  36. Scrope

    I Iron bar wrapped with a solenoid

    What is happening within an iron bar/iron core when it is wrapped by a solenoid with current running through the solenoid? Do electrons within the bar get displaced?
  37. A

    Is Solenoid Inductance Proportional to Turns Squared?

    Homework Statement In Solenoid, is emf E= N. d(phi)/dt, or is it simply d(phi)/dt? Some books contain the latter one. It was not a big deal until i gave a thought about it. Since increasing the N, we are actually increasing the value of n, thus increasing B= (mu) .n.I So, by placing N in front...
  38. T

    Calculting the length of a solenoid

    Homework Statement Q2 A Cu wire of circular section and diameter 0.2 mm is used to form a one-turn coil and also to form a solenoid. Both have a radius of 2 cm. In both cases, a 10 mA current flows through the wire. a)Work out the magnetic field H in the centre of the one-turn circular coil...
  39. Alettix

    Magnetic field decay in cylinder coaxial with solenoid

    Homework Statement For a medium of conductivity ##\sigma##: $$ \nabla^2 \vec{B} = \sigma \mu \mu_0 \frac{\partial \vec{B}}{\partial t} + \mu \mu_0 \epsilon \epsilon_0 \frac{\partial^2 \vec{B}}{\partial^2 t} $$ A long solenoid with ##r=b## has n turns per unit length of superconducting wire anc...
  40. Who Am I

    Inductance of a Solenoid Around a Conducting Sphere?

    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...
  41. WeiShan Ng

    Direction of the magnetic field around a solenoid

    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...
  42. S

    Electric Field induced by a Magnetic Field inside a Solenoid

  43. Ron Burgundypants

    Altered inductance around a solenoid in a cryostat (from Eddy currents?)

    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...
  44. B

    Homemade electromagnet, considerations - strength

    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...
  45. Conductivity

    Derivation of magnetic field of a Solenoid: Biot savart law

    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...
  46. E

    How Does Current Direction and Charge Flow in a Solenoid-Wire System?

    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...
  47. A

    Magnetic field of circular loops and solenoid

    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?
  48. _maxim_

    Moving a solenoid coil in a strong magnetic field

    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...
  49. A

    Mutual inductance of a coil inside a solenoid

    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...
  50. C

    Induced EMF in a coil outside a solenoid

    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...
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