Magnetic fieldlines on a hor5/7/2023 If the first finger points in the direction of magnetic field and the second finger in the direction of current, then the thumb will point in the direction of motion or the force acting on the conductor. It states that stretch the thumb, forefinger and middle finger of your left hand such that they are mutually perpendicular. The direction of the force on a current-carrying conductor in a magnetic field is given by Fleming’s left-hand rule. (iv) If the current around the face in the loop is in an anti-clockwise direction, then it will behave like the North Pole and vice-versa.Īn electromagnet is a coil that attains magnetism due to flow of current. (a) increasing the number of turns of wire in the coil (iii) The magnetic field produced by a current-carrying circular coil can be increased by (ii) The direction of the magnetic field is found by right-hand thumb rule. (i) The strength of the magnetic field B produced by a straight current-carrying wire at a given point is directly proportional to the current I and inversely proportional to the distance from the wire r. Magnetic filed around a current carrying conductor: (vi) The magnetic field lines never intersect each other.Ģ. (v) The magnetic field lines are crowded near the poles (region of a strong magnetic field). (iv) The magnetic field lines originate from the North Pole of a magnet and end at its South Pole outside the magnet. (iii) The imaginary lines representing the magnetic field around a magnet are known as magnetic field lines. (ii) The magnetic field is a vector quantity. (i) The region surrounding a magnet or a current-carrying conductor in which its effect can be experienced i.e., its force can be detected, is called a magnetic field. If you have a more complicated magnetic system, these field equations will no longer hold.1. Note: This is the field line equations only for a magnetic dipole (a regular magnet). So a plot of these equations will give you lines that look like the ones you see in textbooks and Wikipedia. Where $B_r$ is the radial component of the magnetic field and $B_\theta$ is the angular component. A plot of these equations will help you visualize what the field lines look like.Īs this guy at Physics Forum has explained, the equation for a magnetic field line (in polar co-ordinates) in 2 dimensions is given by $$\frac$$ That's all there is to it, really.īut since it is after all just a curve in space, it has to have an equation. The magnetic field lines (or electric field, or any field lines for that matter) are defined such that the tangent to the field line at a point gives the direction of the field at that point. But I'm just adding a couple of points that may (or may not) help your understanding of this. I think Crazy Buddy has covered most of it. Still, if you aren't able to follow, have a look at " how tangents are drawn". The needle would align tangentially to the magnetic lines of force. What are tangents then? Place a magnetic compass somewhere in a magnetic field (say, a bar magnet like the one below). Or, just use a bar magnet instead of catching a live-wire. And the direction of this field is given by Maxwell's right hand cork screw rule. The filings rearrange themselves in the form of curves. Pass some current through the wire and tap the board gently. These field lines are best understood by a home-experiment which has been followed for years. The crowding or sparsity of these field lines depend upon the intensity of the magnetic source. And, they're always continuous closed loops extending throughout the magnetic source and never intersect each other. They're thought to flow but, no actual movement occurs. The direction of these lines is from North pole to South pole outside the magnet whereas in the inside, it's the other way around. These concepts of field lines were introduced by Faraday and both of these fields are related by Maxwell equations. The other properties are almost similar for both. In case of electric field lines, the term unit charge is used. These lines are imaginary straight or curved paths along which a free (isolated) pole would travel when placed in magnetic field. Both electric and magnetic field lines are introduced as an aid for visualizing these fields.
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