Solenoid Definition and 752 Threads

Consider a solenoid with length L and N turns of wire wound around it, filled with a rod of permeability \mu .I want to calculate the magnetic field it produces on a point P on its axis and outside it.The angle between the axis and the lines drawn from point P to a point on the nearest and...

What will happen If I place a magnetic needle inside a solenoid, I mean will the South Pole of the needle be directed towards the South Pole of the solenoid since it is north from inside and the same way regarding the North Pole

Homework Statement (a) What would have to be the self-inductance of a solenoid for it to store 9.3 J of energy when a 1.56-A current runs throught it? (b) If this solenoid's cross-sectional diameter is 3.85 cm, and if you could wrap its coils to a density of 10 coils/mm, how long would...

I am trying to understand why the magnetic field outside a solenoid of very long length can be assumed to be near zero. I gather that the field inside the solenoid will be very dense and therefore strong, and that the field lines that loop back round outside the solenoid can spread out. Is...

If I have a solenoid in the shape of a toroid (i.e. solenoid joined end to end) the magnetic field produced by the flow of charge will produce a concentrated magnetic field within the coil. How would I go about calculating the size of the magnetic field outside of the coil due to magnetic...

Hi Everyone, I'm trying to make a homemade solenoid to lift a metal slug, and i have a 2000mah / 7.4 V / 20C lithium polymer battery. Is this battery going to be sufficient? Here is a photo of my current setup without the battery: side view top view Thanks in advance!

Hi. I have a solenoid, of length l, radius r, which has n turns of copper wire wound on it, carries a current of I amperes, and has a ferromagnetic core of relative permeability μr. How do I determine the magnetic field at a point in free space, x meters from the center of the solenoid? Also...

Consider an ideal solenoid (no resistance, no leakage reactance etc.) connected across an AC supply. The back EMF induced in it will be exactly equal and in opposite direction to the source voltage (which means that when a certain terminal of the AC supply is positive, the side of solenoid...

1. Assuming that both the windings of a transformer is wrapped around an iron core, how is an EMF induced in the secondary winding - isn't it necessary for flux to cut through the winding in order to induce an EMF? The flux cutting through the winding would apparently be very low..as most of it...

Homework Statement An aluminum ring of radius 5.00 cm and resistance 3.00 × 10–4 Ω is placed on top of a long air-core solenoid with 1 000 turns per meter and radius 3.00 cm. Over the area of the end of the solenoid, assume that the axial component of the field produced by the solenoid is half...

I have come across this problem, who to determine the direction of induced current. It keeps me wondering why the answer that i got is Fleming's right hand rule? Aren't it should be Right hand grip rule? Cz the usual and conventional way of inducing electricity in a solenoid is to pass the...

Hi- I'm trying to build a simple linear motion control using a solenoid. I've replaced the typical steel core for a permanent magnet core so that I can both push the armature out and pull it back in by flipping polarity (and without using any springs). This works nicely. Unfortunately, it still...

Hi, First post, and this stuff is way above my head so i am hoping some one can help me. So what I am after, i am after building a solenoid to to open a valve, this valve is holding back around 3000psi compressed air. its from a pressure washer gun. and takes quiet abit of force to open...

So I was reading a thread on PF talking about the radius of a solenoid and Bob S answered with a link: On that site, it states that the Radius = the outer radius - the inner. It doesn't make sense. What happens when there is only one layer of coil and the outer radius (OR) is basically the...

Homework Statement A solenoid with a large number of turns of wire is connected in series with an ammeter and a battery. An iron rod is moved towards the solenoid at constant speed. What will happen to the reading on the ammeter (A) as the rod moves closer to the solenoid, before...

http://img42.imageshack.us/img42/6336/14vu.png please explain your answer! also if u know of similar problems or where this problem is taken from do tell me coz i have an admission exam coming up soon please explain the following: 1. what is the flux like? 3. how the coil spins? z. how is...

I'm a Physics student currently working on some research with my advisor. My advisor doesn't know much about modeling solenoids so I've been tasked with reaching outside for help. I did that, but I can't remember the formula or the guy's name so I'm turning to you guys for help. There is some...

I'm a bit confused with the equation for a long solenoid. The usual derivation has us consider a rectangular loop enclosing N number of currents over the length L through it. So by Ampere's law one gets B=μNI/L. The currents and the loop look like this right? --------- | . . . . |...

Homework Statement A solenoid that is 117 cm long has a cross-sectional area of 20.0 cm2. There are 1010 turns of wire carrying a current of 9.56 A. (a) Calculate the energy density of the magnetic field inside the solenoid. (b) Find the total energy in joules stored in the magnetic field...

Homework Statement A long solenoid of radius R, length L (which is much longer than R), number of windings N, has a current I that is changing in time at a rate (dI/dt). What is the magnitude of the electric eld a distance R=2 from the axis of the solenoid? Homework Equations...

Homework Statement When putting a magnet into a solenoid, under what conditions is a current generated? The Attempt at a Solution In order for a current to be generated, the magnet needed to be moving as it passed through the solenoid. This is due to Faraday’s law, which states that an...

Hi, I've seen a couple of posts in the Homework section of Physics Forums about the fields of solenoids, but neither of them seem to address the problem that I have about it. The set-up is a long solenoid that has a sinusoidally varying current going through it. We can establish that the...

I wanted to mention that this solenoid has many winds over many layers. The thickness of the windings is 2.4 inches coming off of the engineering schematics, and has many many many turns, which is unknown. It has a 6T field at the zeroth point on-axis. I'm doing research with a professor and...

What would be the best method to model a solenoid? I tried writing a program that calculated the off axis elements of the solenoid but the value came out wrong. Any idea?

I have a question about solenoids. The formula for the magnetic field energy density is: \frac{1}{2}\frac{B^{2}}{μ} If I have an air-filled core, then μ=μ0. If I have a steel core, then μ will be ~ 100μ0. This implies that an air-filled core solenoid stores more energy than a steel core...

Homework Statement The figure below shows a short coil which is coaxial with a very long solenoid (you may approximate it as infinite.) Coil: Has 120 turns of radius 1.8 cm and resistance 5.8 . It is not attached to anything. Solenoid: Has 22700 turns/m and a radius of 1.6 cm. It receives an...

Homework Statement Describe the Faraday effect as it might be observed in a glass cell contained within a solenoid Homework Equations The Attempt at a Solution When a glass cell is immersed in a strong magnetic field, the plane of vibration of light waves is rotated. When...

Homework Statement Consider a solenoid with a time varying current and with a coil of wire placed around it. Suppose there is a soft iron rod inside the solenoid. My question is: What happens to the (induced) current in the coil of wire as a result? Homework Equations Faraday, magnetic...

Homework Statement https://www.dropbox.com/s/17hsoz0zdfoston/Screen%20shot%202013-05-10%20at%2012.37.44%20PM.png 1) A voltage is applied to a solenoid such that a current is flowing in the indicated direction. Inside the solenoid is a single wire loop that is oriented in the same...

Hi guys. This is for an engr project that I am involved in. I have everything else worked out but this got me stomped. I've been searching for a while and can't find something that fits my application. basically the solenoid is controlling a dual acting air pneumatic cylinder. the solenoid...

Hello! I understand that by increasing the number turns the magnetic field is strengthened. But would that "extra" turns demand more power input from the power source?

I understand that the magnetic field at points inside the solenoid is the vector sum of the B field due to each ring. How can the field inside be uniform then since if you consider just one loop in the solenoid the value of the B field is different at different points in that circle or loop.

Homework Statement Inside a very long, straight and hollow plastic tube (R << L) we have ionized liquid moving at a velocity v = 100 m/s. The net charge per unit volume is n = 106 electrons/m3. The radius of the tube is R = 10cm. Around the tube we have a solenoid, with n = 100 loops/m...

The B field at the center of a stack of N circular loops each carrying current I is B = mu0 * N * I / (2a) where a is the radius of the loop, derived using Biot-Savart law. The B field inside a solenoid is B = mu0 * N * I / l where l is the length of the solenoid, derived using Ampere's...

I wound 4 layers on a piece of 3/4 conduit. The wire is 20 gauge (.032) and the coil length is 7 inches. I put 5 amperes into the coil and a bolt that fits the conduit didn't move. It stuck to one side of the conduit but it didn't snap in as I expected. What do I do to make this solenoid work?

So I'm building a solenoid that needs to move a load of 5 ounces, 0.4 inches. I'm pretty sure my calculations for the force inside the coil on a iron pin are correct: F = (B^2 * A) / (2 * Uo). Where B is the flux density, A is cross sectional area of pin Uo is permeability of free space...

Homework Statement Sorry for the blurry picture. If the coil is being pulled away from the loop shown to the right, in what direction is the current induced in the loop? Homework Equations right-hand rulesThe Attempt at a Solution I assumed it to be clockwise just from looking at the...

Hi guys, I'm looking for an equation and/or proof of the magnetic field produced inside a solenoid with a finite length (hence, it shouldn't just be "muNOT n I." For some reason I can't find a simple proof anywhere. I have no idea where to start. ampere's law obviously doesn't work, and that...

something that has had me confused: How can I calculate the time varying magnetic field produced by a solenoid, outside the solenoid along the axis of the core. I know that: inside the solenoid : apply amperes law For DC (magnetostatic) case outside the solenoid : apply Biot-savart law...

Homework Statement As a new electrical technician, you are designing a large solenoid to produce a uniform 0.170 T magnetic field near the center of the solenoid. You have enough wire for 4200 circular turns. This solenoid must have a length of 1.10 m and a diameter of 1.50 cm. What current...

Homework Statement A coil of wire with N turns is placed around the a long solenoid with n turns per unit length carrying a current I as shown below, A)If a current I flows through the solenoid, derive an expression for the magnetic flux through the coil and explain why the size and shape...

I know that the answer will not be a or c due to effects of gravity. But I can't decide between b and d. I chose b because of lenzs law. I thought that since the south pole enter first, there will be an increasing flux upwards, coil opposes this by inducing an magnetic flux downwards. When it...

Ended up figuring out how to solve this problem. I just was not expecting certain parts of the results which lead me to believe I did it wrong.Homework Statement Voltage of battery is 5V Resistors are 5 Ohms The solenoid has no internal resistance 1.Need to find V_2 before switch is opened...

I'm trying to figure out how to calculate the actual physical force on a solenoid plunger. I.E what kind of load it can pull or push. So if I setup a magnetic circuit and calculate the flux going through it at maximum airgap, am I right to assume that the force is equal (B^2 * A) / (2*u)...

Just need a question cleared up. If I had a coil wrapped around a core, and I was calculating the magnetic field of the solenoid using B = μnI where n = N/L, I is current and μ is the permeability of my material N being the number of turns in the coil, and L being the length of the...

If instead of a disc shaped end I have a conical end , would there be any change in the measured magnetic field strength at the end of the solenoid keeping current, core and number of turns per unit length constant ?

Hello, I found an approximation for this log function: log \Bigg(\frac{\Lambda}{\rho} + \sqrt{1 + \frac{\Lambda^2}{\rho^2}} \Bigg), where \Lambda \rightarrow \infty . The above is approximated to the following, -log \bigg(\frac{\rho}{\rho_o} \bigg) + log \bigg(\frac{2 \Lambda}{\rho_o}...

URGENT: solenoid and superconductor questions Sorry I cross posted this, but I realized that general physics was probably a better place for it... I have a few questions regarding the levitation of a piece of superconductor using the field from a solenoid. In other words, I want to calculate...

Hey everyone, I am currently attempting to determing the leakage flux (for all intents and purposes) from a solenoid (DC current) with various core shapes and sizes. I have tried doing this using Comsol and Feko, but so far have been unable to. Does anyone have any knowledge of either of these...

Homework Statement From this video: http://www.youtube.com/watch?feature=player_detailpage&v=mdZo_keUoEs#t=77s it shows that the steel rod will eventually stay in the middle of the solenoid. At first the magnetic field of the solenoid would look like...