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.
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...
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...
Hello,
I know how a plunger in a pull solenoid is pulled to the center of the solenoid. What I am wondering is the following. Does the plunger experience a centering force towards the center of the coil? If the plunger is moved slightly off-axis from the center of a circular coil, will the...
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
Homework Statement
Homework EquationsThe Attempt at a Solution
The answer of 2c is : Current through A to the left.
But I think it is to the right.
By I=V/R, a reduced resistance R results in an increase of current through solenoid X. By B=unI, an increase in current causes the magnetic flux...
Our professor did a demonstration today for our physics II class. She was demonstrating electromagnetic induction with a solenoid and a metal ring. When she slid the ring down the solenoid and passed alternating current through the solenoid, the metal ring was flung upward off the solenoid.
My...
Hello everyone! I found in my textbook that in order to calculate the pressure experienced by the surface of a long straight solenoid with ##n## turns per unit length and current ##I## we don't use the typical magnetic field ##B=\mu_0nI## on a loop of the coil , but a corrected magnetic field...
Homework Statement
A coil with 140 turns, a radius of 5.2 cm, and a resistance of 11.0 Ω surrounds a solenoid with 200 turns/cm and a radius of 4.5 cm. The current in the solenoid changes at a constant rate from 0 A to 2.0 A in 0.10 s. Calculate the magnitude and direction of the induced...
I'm currently in conceptual phase of designing a coil gun. Thinking back to my physics 2 class-- and some of my independent studies-- I understand an EMF produced by a solenoid with current through the wires of it is strengthened significantly by a ferrous core, as seen by the classic experiment...
This is not a specific homework problem. It is a lack of understanding in theory relating to a lab report I have to write.
We (my group and I) wrapped a 40 cm PVC pipe in copper wire (very densely and for almost the entire length), applied a current to it, and dropped a permanent magnet...
What happens if I have a permanent magnet outside an ideal solenoid? Does the permanent magnet rotate until the system reaches an energy minimum in its magnetic fields? Or does the permanent magnet fail to rotate because the magnetic field of the solenoid does not reach the magnet? Wouldn't...
Homework Statement
For a lab we need the equation of the magnetic field strength produced by a solenoid a distance r away from it (outside of it). I tried looking online and couldn't find one that didn't involve a bunch of cross products or similar. Wonder if anyone knows the formula? I know...
Homework Statement
A long air-cored solenoid has two windings wound on top of each other. Each has N turns per metre and resistance R. Deduce expressions for the flux density at the centre of the selenoid when the windings are connected (a) in series, and (b) in parallel, to a battery of EMF E...
Homework Statement
Dr. X has an infinitely long superconducting solenoid with n turns per unit length and a power supply to drive arbitrary current wave forms through the solenoid's winding. The power supply can drive DC currents, temporarily ramped currents, sine wave currents, etc...