Hi! roshela, im an ECE student, i have some questions... 1) what is the relationship between current in a wire and a magnetic field? 2.) how does the amount of current in the coil and the type of material affect the strength of an electromagnet? ---i really need some answers for my lab report... THANKS!!!!
the relationship between current in a wire and a magnetic field (in the case magnetic induction or magnetic flux density) is given by biot-sevart's law B= ∫ (υ/4pi) (i*dl*sin θ )/(r*r) where b is the magnetic induction dl is a differntial length of conducting element i is the current thru the differntial length of conductor r is the distance of a point from the wire at which B is measured (υ) is the permeability of the medium direction of B is given by the Right hand screw Rule for cross product of vectors in vector form the equation is given by B = ∫ (υ/4pi)(i* dl*r)/(r*r*r) where dl is the vector representing the length dl in the direction of current i r) is the radius vector directed from the differential element dl to the point at which B is measured As you can see the value of B is indeed dependent on the value of i and the value of υ (which depends on the medium )..ie the value of B in iron (a ferromagnetic material) is much greater than the value of B in free space..thats why we use an iron core in electromagnets the value of B in turn determines the strength of the electromagnet
If you require any further information refer to the following chapter here at AAC: Volume 1 Chapter 14: Magnetism and Electromagnetism