What is Solenoid: Definition and 741 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. G

    Plunger Force of Solenoid: Am I Missing Something?

    Maybe I'm just dense, but... I searched for forum for "solenoid" and I still haven't found the answer that I'm looking for. Mainly, I want to know if there is a general equation for the plunger force of a solenoid-type linear actuator. I understand that the force of the plunger is related...
  2. X

    Where to Buy Magnet Rod for Solenoid? Find Out Here!

    Hi... I'm doing a solenoid for my project. But I don't know where to buy the magnet rod. I had look for a lot of place but doesn't have the magnet. Do anyone here know where can I get the magnet? Thank you.
  3. F

    I just need to work re-checked, current in solenoid

    Here's the problem I am solving: The current in a solenoid with 22 turns per centimeter is 0.50 A. The solenoid has a radius of 1.5 cm. A long, straight wire runs along the axis of the solenoid, carrying a current of 31 A. Find the magnitude of the net magnetic field a radial distance of...
  4. A

    Calculating Solenoid Turns: Magnetic Field, Current, and Dimensions

    (a) How many turns of wire would be on a solenoid carrying a current 4.9 A if the solenoid is 20 cm in diameter, 248 cm long, and the field at the center is 3.3 × 10-3 T? The magnetic field of a solenoid is the permeability of free space times the number of turns per unit length times...
  5. K

    Solenoid current physics problem

    A solenoid has a field of 1.5 T when the current is flowing in it. Its cross-sectional area is 0.30m^2. Another solenoid with 150 turns and a resistance of 20 ohms is wound tightly around the original solenoid so that both solenoids have the same cross-sectional area. The current in the first...
  6. J

    Controlling Solenoid Valves & Sensors with Microcontroller

    Hi, I'm trying to control some solenoid valves and sensors with a microcontroller and I'm not sure what type of circuitry might be used to best accomplish this. For the outputs I think a ULN2003AI made by Texas Instruments might work but for the inputs I'm not real sure what I need to take...
  7. C

    Solve Solenoid Resistance/Magnetic Field/Length

    It is desired to construct a solenoid that has a resistance of 9.29 ohm and produces a magnetic field at its center of 0.0642 T when it carries a current of 7.32 A. The solenoid is to be constructed from copper wire having a diameter 0.895 mm. The resistivity of the copper is 1.7x10-8 ohm-m...
  8. M

    Designing a Solenoid Driver Circuit - Max Force of 2.75 lb

    Hi, I am designing a solenoid driver ckt. The solenoid can hold a max force of 2.75lb. If I want my ckt drives the solenoid with max force, what current or power the ckt need to draw? Thanks for any help. Mike
  9. M

    Solenoid force to electrical current

    Hi, Please remind me of formulas to convert the mechanical froce (lb) to electrical current (I) or power (W)? Thanks Mike
  10. M

    .Using a LM555 Timer to Power a 6V Solenoid

    Hi everybody, I have set up a 555 monostable timer to run a solenoid for 0.05 seconds - very rapid on then off, moving the solenoid about 3 mm. I have found that it is not producing quite enough force for what I need and was wondering if I put 6 vdc solenoid in place of the 12vdc solenoid...
  11. P

    Solenoid induced EMF problem

    A 1 m long large coil with a radius of 15.2 cm and 280 turns surrounds a 7.6 m long solenoid with a radius of 5.2 cm and 3200 turns. The current in the solenoid changes as I=I_0 sin (2\pi f t) where I_0= 30 A and f=60 Hz.Inside solenoid has 3200 turns and outside coil has 3200 turns. The...
  12. P

    Induced Current in Aluminum Ring Around Solenoid

    An aluminum ring of radius 5 cm and resistance 0.003 ohms is placed around the center of a long air-core solenoid with 1000 turns per meter and a smaller radius of 3 cm. If the current in the solenoid is increasing at a constant rate of 270 A/s, what is the induced current in the ring? B=...
  13. C

    Model Electron in Solenoid: Path & Frequency Effects

    I'm tyring to develop some equations to model the path of an electron beam in a magnetic field. It starts out with a velocity in the z direction but also a tangential velocity, that sets up a helix given by x(t) = (E/(wB))[cos(wt)-1] y(t) = (E/(wB))[sin(wt)-wt] z(t) = vt where v and k and...
  14. Reshma

    What is the electric field outside a solenoid in quasi-static approximation?

    A long solenoid with radius 'a' and 'n' turns per unit length carries a time-dependent current I(t) in the \phi direction. Find the electric field (magnitude and direction) at a distance 's' from the axis (both inside and outside the solenoid), in quasi-static approximation.What's quasi-static...
  15. D

    Magnetic Field and Electric field outside a long solenoid

    Hello, The question goes like this: A long solenoid has n turns per unit length and carries a current given by I=I₀sinωt. The solenoid has a circular cross section of radius R. Find the induced electric field at a radios r from the axis of the solenoid for (a) r<R (b) r>R Well, i got...
  16. F

    Help with Solenoid Valve specs

    I'm currently part of the propulsions team for a hybrid rocket project here on campus, working on the liquid fuel injector system. Specifically I'm trying to model which injector designs give us the best burn rate over the entire burn. However, I'm a physics major, not an engineering major, so...
  17. A

    Magnetic field for a single-layer solenoid

    does anybody know why the magnetic field for a single-layer solenoid of a point in the middle of the solenoid axial field is H=[(4pini)/(10L)]*{[L+2x/[2(D^2+(L+2x)^2]^(0.5) + [L-2x/[2(D^2+(L-2x)^2]^(0.5)} where L is the length of a finite solenoid, D is the diameter
  18. M

    Measuring magnetic field of a solenoid

    hi I need an experiment to measure magnetic filed in a solenoid. could anyone help me?
  19. T

    Finding Resistance and Inductance of solenoid

    The inductance of the solenoid determines the time it takes to establish this current. Find the inductance,the resistance, and the time constant of a solenoid that is constructed by wrapping five “tightly wound” (i.e., wire-against-wire like this ) layers of 0.30 mm diameter copper wire on a...
  20. P

    Core Material for Long-Run Solenoid Circuits

    http://img16.imagevenue.com/img.php?loc=loc76&image=054_doorbell1.jpg I am building a circuit such as the one above. The only difference is that it will be running for long periods of time. So heat becomes an issue. To make the most efficient and strongest electromagnet I am wondering...
  21. C

    Designing Big Solenoid for Physics ISU - 100-200VDC 2-7A

    Im building a big solenoid for my physics ISU and i was woundering on how it should be designed. I plan on supplying around 100-200 volts DC to it, at very low current, maby 2-7 amps. The question is this, does the solenoid have to have a specific length or number of coils, or a certain...
  22. L

    Solenoid 30cm long and 8cm in diameter

    [B]You have a 12 volt car battery and a supply of #18 gauge copper wire. If you make a solenoid 30cm long and 8cm in diameter, winding two layers of wire along the length of the solenoid, what will be the strength of the magnetic field at teh center of teh solenoid when connected to the car...
  23. S

    One-Stage Solenoid: Wrapping the Wire for Optimal Turns

    I want to make a very powerful one stage solenoid. The pipe is only so long , so if I wrap the wire evenly I will only achieve a fixed number of turns. If I wrap the same wire of that one with the current flowing in the same directon I should get twice as many turns altogether. The problem is I...
  24. D

    Calculating Energy to Rotate Magnetic Dipole in Solenoid

    i received this problem from my lecturer A solenoid is wound with 2200 turns per meter, and carries a current 2.5A. Take the axis of the solenoid to the solenoid to be parallel to the z-axis. A magnetic dipole moment given (m)=(20A.m^2)i+ (30A.m^2)k is located inside the solenoid. i)how...
  25. R

    Create Soda Can Launcher with Solenoids | College Student Project

    As a college student I have a lot of extra soda cans around I thought it would be neat to tryto have some fun with them. What I would like to do is make some sort of solenoid or system of solenoids that would launch a soda can. What I am wondering is if an aluminum can is afected at all by the...
  26. K

    The length of a wire forming a solenoid

    I need help! I am unsure of what to do. A solenoid 1.33 m long and 0.0260 m in diameter carries a current of 17.8 A. The magnetic field inside the solenoid is 22.4 mT. Find the length of the wire forming the solenoid. The only information I have is the equation B=(Mu sub 0)*n*i Where...
  27. B

    Effects of Water on Magnetic Field Outside a Finite Solenoid?

    I can`t seem to find any information on how to calculate the magnetic field outside a real finite solenoid. I do not need the field on-axis, but rather perpendicular to the solenoid. Any ideas on how to proceed, or suggestions to literature? Thanks Indian
  28. G

    Formula for magnetic field of solenoid

    Hi! I need formula for magnetic field of solenoid on axis of solenoid in some distance from center.Also I need something about interaction magnetic field on material point(interaction solenoid on material point).I want to know force that infuence on material point. Thx in advance and sry for my...
  29. Y

    Infinite solenoid with magnetic flux

    Hi, I have a question as follows. For an infinite solenoid with magnetic flux \Phi, for what values of \Phi "is the quantum mechanical motion of an electron constrained to stray far from the solenoid exactly the same as it would be if \Phi were zero"? Solution: \Phi = n \Phi_{o} with n =...
  30. I

    A solenoid where radius length?

    i've found a lot of equations and relations about solenoids where the lengh tis always much greater than the radius, but what if the radius was much greater than the length? PS. also does anyone know an equation that could help me figure out the magnetic field strength outside a solenoid? or...
  31. Cyrus

    Solenoid Problem: B Field Constant on Plane of Loop

    Lets say there is a single loop of wire. Is the B field at exactly of the plane of the loop going to all be perpendicular and of constant magnitude, at exactly the plane of the loop. I know this is true for the center. Doesnt it also hold for points off center of the loops axis, as long as we...
  32. J

    Quick Question about the mag field of a solenoid

    A light bulb and a solenoid are connected in series to a battery. An iron rod is thrust rapidly into the solenoid and later rapidly removed. The bulb: 1)No change in or out 2)No change in, brightens out 3)Dims in, Dims out 4)Brightens in, dims out 5)Brightens in, brightens out 6)remains...
  33. M

    Self inductance of a solenoid

    hey, i was just confused here, which is the right formula for finding the self inductance of a solenoid, given the number of turns, the cross-sectional area, the length, and the current. is it L = Uo x Ur x N^2 x A / L (Uo = mu o, Ur = mu r)?? pls if it is wrong, let me know the right...
  34. C

    Magnetic field of the solenoid can be represented by the voltage

    According to which law the magnetic field of the solenoid can be represented by the voltage induced in the search coil ? :rolleyes: :biggrin:
  35. P

    What is the inductance of a solenoid with a soft iron core?

    A solenoid has 140 turns uniformly wrapped around a soft iron core, which has a magnetic permeability =750 Uo (mue sub-knot) diameter of 10.0m and a length of 9.00cm. What is the inductance in milli-henry (mH)? Did I set this up right? Using L=(uN^2A)/length, you get...
  36. C

    Magnetic Field outside AC Solenoid

    Hi I have scoured the internet trying to find the right expression to calculate the magnetic field (B) outside of an AC driven solenoid. All i keep getting is stuff for DC driven or inside the solenoid. Can anyone help? thanks Craig
  37. K

    Calculating Inductance of a Tightly Wound Solenoid

    I can't seem to figure out how to solve this problem. If you are given the solenoid length and diameter. And told it consists of a single layer of tightly wound wire with the diameter of the wire given, the change in current thru the wire given, and the change in time given how would you find...
  38. A

    Relationship between Magnet Rotation Speed and Induced Voltage in a Solenoid?

    Hello all, We've been studying electromagnetism and motors in physics. I was just wondering, if you placed a rotating magnet near the end of a current-carrying solenoid, what would the relationship be between the magnet's speed of rotation and the induced voltage in the solenoid? Thanks
  39. B

    Help My Lawn Mower Won't Start - Solenoid Troubleshooting

    Hello. My ride-on Lawn Mower broke down recently. And I'm not a real mechanics or automobile person so please help me out. (it requires a bit of knowledge on circuits) When I turn on the ignition, usually the engine rev's a bit. And then I try it a couple times until it works. Takes about 2~3...
  40. A

    Would the Induced Current Change Direction Inside a Solenoid with a Search Coil?

    if we were to insert a search coil inside a solenoid, (plane of coil perpendicular to B), would the induced current change direction in the middle of the solenoid ? it would have to wouldn't it since it would now be approching the opposite pole --- ??
  41. N

    Apply the ampere's law to the infinite solenoid

    how to apply the ampere's law to the infinite solenoid... how we find the equation for the magnetic field ?? who can help...
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