Induced emf Definition and 251 Threads

When I induce magnetic flux through a closed loop, I should expect the lines of flux produced by current in that loop to oppose the change of flux through that loop. But what happens when that loop, say a rectangular loop, is curved into the shape of the letter J (like a candy cane) and my flux...

Homework Statement The figure below shows a closed loop of wire that consists of a pair of equal semicircles, of radius 7.0 cm, lying in mutually perpendicular planes. The loop was formed by folding a flat circular loop along a diameter until the two halves became perpendicular to each other...

Homework Statement [/B] Three conducting loops, all with the same resistance ##R## move towards a uniform and constant magnetic field, all with the same velocity ##v##. Their relative sizes can be identified by the grid. As the loops move into the magnetic field an induced current begins to...

Homework Statement In the very long wire conductor as shown on the picture , flows a current magnitude I. Near the wire there is a square shaped contour , with length a ,which rotates around its axis a constant angular velocity. Axis of square contour and a straight line conductor are...

Homework Statement A 4.0 cm diameter coil (1000 turns) is at rest in the XY plane. The magnetic field in this region of space is given by B=(0.30i + 0.50t2 k) What is the induced EMF in the coil at t=2.0 seconds Homework Equations ε=dΦ/dt Φ=ABcosθ The Attempt at a Solution ε=[/B]d/dt(...

Homework Statement Magnetic Field B is going into the plane. Bar is moving to the right with velocity v. Neglect resistance of the conducting bar and all contacts. a.) Determine the induced emf in the circuit. b.) To maintain the uniform motion of the conductive bar, there must be an external...

Homework Statement A long, straight wire has a line charge, λ, that varies in time according to: λ = λ0 exp(-βt). A square wire loop of dimension a is located adjacent to the wire at a distance of a from the wire. Calculate expressions for the displacement current at the center of the wire loop...

Homework Statement There is a magnetic field directed inside/ towards the screen. There is also a single rectangular coil parallel to the screen where one of the sides are movable. The magnetc field increases, what happens to this movable side of the coil. This is my description of the...

Homework Statement Lets say we have two horizontal rails connected by a resistor to the left, and we have a movable conducting rod that slides without friction on the rails.There is a uniform magnetic field going into the page. Homework Equations F = ILB[/B]The Attempt at a Solution Now, I...

I read many different explanation but none of them is satisfying. There is two cases: 1. I move an iron rod in a magnetic field, between two bar magnet for example. To this case I read that when I move the rod the electrons on it also move and moving charges produce magnetic field which...

Homework Statement Question I need help with: If wire AB of problem 9 moves with a velocity of 50.0 m/s to the right, at what rate should B change when the wire is at a distance of 5.00 cm from the left end of the loop, such that there will be no induced emf in the circuit? Answer: 300 T/s...

From this diagram: If a conductor of length(##L##) is moving with a velocity(##v##) inside constant magnetic field(##B##), there is an induced EMF as indicated at the top of copper slab, and connected to a load and current will flow. I've been curious with the way the wires are connected to...

If you have a one solenoid inside another (with the same number of coils of wire) the current is going through the inner one. How does the induced EMF in the outer one depend on the frequency of AC in the inner one

Let's say I place two different size conducting loops inside of a uniform magnetic field. For the sake of the diagram I have the loops share a point, but just treat them as though they are not touching. Then I decrease the value of the magnetic field very quickly. \frac{dB}{dt} =...

Assume we have the following copper slab, with volume ##V##, and introduced a magnetic field covering a small area of it like so: There is change in magnetic flux(##\phi##) due to the magnetic field increasing/decreasing, and via Faraday & Len'z law of electromagnetism, there is an induced...

If we have a conducting loop, and a magnet (say North pole first) is pushed into it; that induces and emf and hence a current in the coil due to the changing magnetic flux, right? According to Lenz' law, the direction of the current is such that it opposes the change. So from the side the magnet...

I see a lot of problems on constant current inducing a current in another wire due to its associated magnetic field, but not so much a single wire's induced electric field. If the current along an infinitely long wire is flowing out of the page and inducing a counter-clockwise spinning magnetic...

Homework Statement There's a primary and secondary coil. The primary coil has 15 turns, and the secondary coil has 16000 loops. The 25000 V is applied to the primary coil, what will be the induced emf in the secondary coil. Homework EquationsThe Attempt at a Solution Very confused as to how...

Hey people I was wondering why is an emf induced in a loop which moves perpendicular to a uniform magnetic field. I mean, say the loop is a square of area r^2, and moves in the xy plane, where there is a uniform magnetic field B in the z direction. Why will an emf be induced? The flux remains...

Hi everyone, I am currently stuck on this problem, and I was wondering if I could get assistance, at least in getting started. It'd be greatly appreciated!

The prevailing wisdom is that coiling excess signal cable under an MRI magnet for storage in a figure-8 configuration will reduce or eliminate induced noise onto the cable from the pulsing fields from gradient coils. I am starting to doubt this, however. A quick diagram of a figure-8 looped...

Homework Statement Homework Equations Faraday's and Lenz' law. emf = -d(ф)/dt The Attempt at a Solution The current is increasing upwards during that time interval. Thus, by Right-Hand-Rule, the magnetic field goes into the page at the loop. Lenz' law says that the loop's induced emf...

Homework Statement A square conducting loop lies in the xy plane of an xyz coordinate system. The loop is in a uniform magnetic field that points in the positive z direction and is decreasing at a rate of 0.070 T/s. What are (a) the magnitude of the induced EMF in the loop and (b) the direction...

Homework Statement It's Problem 6.6 on this page: http://web.ece.ucdavis.edu/~lxgliu/eec130a/2012winter/hw9s.pdf It has the solution and everything. I don't understand part (b) though. Homework EquationsThe Attempt at a Solution [/B] For part (b), I thought the direction of the induced...

A Power supply is connected to a parallel circuit with resistance R, there are three wires connected in parallel where the voltages would be the same,however, the current would be dived based on the number of wires and the resistance is the same. What would happen if wire (c) was placed in a...

I am having trouble understanding a process in the electric motor. using this website as a frame of reference (http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/mothow.html), as an electric current is passed into that magnetic field, shouldn't the current also be creating a magnetic field, and...

1. A very large loop of metal wire with radius 1meter is driven with a linearly increasing current at a rate of 200amps/second . A very small metal wire loop with radius 5centimeter is positioned a small distance away with its center on the same axis (the loops are coaxial). The small loop...

Homework Statement [This is the best image I could find] The link on the bottom part of the rails is now removed creating two parallel wires that are not connected (so no longer U shaped but just two rails). Now a wire of length L, mass m and resistance R slides without friction down parallel...

Homework Statement A long, straight wire as shown below carries a constant current I. A metal bar with length L is moving at a constant velocity V as shown. Point ‘a’ is a distance ‘d’ from the wire. a) Derive an expression for the EMF induced in the bar. b) Which point ‘a’ or ‘b’ is at a...

From the following diagram: When a wire is placed in a magnetic field ##B##, and current starts to flow within that wire. It creates it's own magnetic field(##B_w##). Will ##B_w## interact with the external field ##B##? If it does, is the result of the interaction the Lorentz force? Also...

Homework Statement [/B] Suppose, there is a 'constant' magnetic field ##B## in the upward direction. A loop of conductive wire(XYZ in the picture, which is connected to a closed circuit with resistance R) is placed horizontally on it. The area of the loop is being increased with time. Will...

Faradays law tells us that a change in flux induces an emf. Now consider the phenomenon of motional emf. It is observed across the ends of an open conductor (ie one which is not in a circuit). It is always discussed in connection to faradays law. Where is the change in flux in the case of a...

to calculate emf i can use the flux rule -d(magnetic flux)/dt or the lorentz force line integral across the circuit. Is there a gudeline to follow for knowing when to use either (or both) of these methods? Thanks :D

Homework Statement Consider the loop in the figure below. What is the maximum induced emf in each of the following cases if A = 600 cm2, ω = 31.0 rad/s, and B = 0.490 T? Rotating about x,y,z? Homework Equations Faraday's law The Attempt at a Solution This should be relatively easy since the...

Homework Statement The current in a solenoid (you may treat it as a long solenoid of length 2.0 m, turns, and radius 0.5 m) is decreasing at a rate of 1.7 A/s. What is the EMF at a point .35m inside the solenoid? Homework Equations B=N(mu_0*I)/(2a) where B=magnetic field, N=turns per...

why does induced emf change in case of generators but remains constant in case of moving conductor?

This thing has confused me for long .I have not come across any satisfactory answers on my own or while browsing through the internet. Everybody has seen the example of a rod moving while on parallel rails, with magnetic field perpendicular to the plane of loop formed by rod and rails...

Homework Statement In the circuit shown in the figure, the switch S is closed at time t=0 with no initial charge on the capacitor. What is the induced emf if the inductor at time t=0? Homework Equations ε=-LdI/dt The Attempt at a Solution Initially the inductor acts like a broken...

Homework Statement (Challenge Problem 80, Ch33) A rectangular metal loop with 0.050 ohms resistance is placed next to one wire of the RC circuit shown in the below figure. The capacitor is charged to 20 V with the polarity shown, then the switch is closed at t = 0s...

Homework Statement A rectangular wire loop, 24mm by 36mm, is placed in a magnetic field. The flux density perpendicular to the loop is decreasing in magnitude at a rate of 0.2Wb/m^{2}/s. Calculate the induced emf around the loop. Homework Equations The problem is I don't know which...

A metal bar with length L, mass m, and resistance R is placed on frictionless metal rails that are inclined at an angle α above the horizontal. The top end of the rails are connected with a conducting wire. The resistance of the rails and wire are negligible. The rails are embedded in a uniform...

Hi everybody, I was wondering how much induced EMF would be produced in a 20cm diameter coil with 100 loops produce. Has anyone conducted such an experiment? I am interested in quantitative values of the experiment. Thanks, KB

Homework Statement A conducting bar of length L moves with velocity v, in a rectangular region with a uniform and stationary magnetic field B_1. Near the bar, there is a cylindrical region of radius R with another magnetic field B_2 (it may vary on time). Both magentic field are normal to the...

Homework Statement A uniform magnetic field B is perpendicular to the plane of a circular wire loop of radius R. The magnitude of the field varies with time according to B=B0exp(-t/τ) where B0 and τ are constants. The time dependence of the induced emf in the loop is a) exp(-t2/τ2) b)...

Homework Statement a coil starts perpendicular to a magnetic field of 0.365 tesla , it has a length of 0.15 cm and a height of 0.25 cm , it rotates with a frequency of 1800 rotation / min . it also has 30 turns calculate the mean induced Emf during quarter a rotation Homework Equations...

> A very long straight wire carries a current I. A plane rectangular coil of high resistance, with sides of length $a$ and $b$, is coplanar with the wire. One of the sides of length $a$ is parallel to the wire and a distance $D$ from it; the opposite side is further from the wire. The coil is...

Homework Statement A wire loop of resistance R and area A has its normal along the direction of a uniform magnetic field, B. The loop is then flipped over in a time Δt so that its normal is opposite to the field. a) Calculate the average induced EMF. b) Find the average induced current. c) If...

A single-turn circular loop of radius R = 0.197 m is coaxial with a long 1740 turn solenoid of radius 0.0410 m and length 0.890 m, as seen in the figure below. (picture in URL)...

Homework Statement I don't understand why the answer in this problem is choice A. http://grephysics.net/ans/9277/57 I'm confused. Lets say the semi circle is FULLY outside of the circle. For awhile after that, the semi circle would be accelerating the rate at which a certain % of it is...

In the classic problem of the induced EMF in a moving conductor (as in the picture above), the calculation for the induced EMF is as follows E=\frac{d\Phi_B}{dt}=\frac{d(BA)}{dt}=\frac{Bd(A)}{dt}=\frac{Bd(Lx)}{dt}=\frac{BLdx}{dt}=BLv. The derivation assumes that the magnetic field B is...