jyoti bhatia
Last Activity: 8 Years ago
Magnetic fields generated by current-carrying wires:
Circular magnetic fields are generated around current carrying wires. Strength of these fields varies directly with size of the current flowing through wire and inversely to distance from the wire.
Assume a diagram in which solid teal circle in the center represents a cross-section of a current-carrying wire in which the current is coming out of the plane of paper.
Concentric circles surrounding the wire’s cross-section represent magnetic field lines.
The rule to determine direction of magnetic field lines is called the ‘right hand curl rule’.
In this rule, your
thumb points in direction of current
fingers curl in direction of B
Equation to calculate strength of magnetic field around a current-carrying wire is:
B perpendicular = µoI / (2πr)
where
µo, permeability of free space = 4π x 10-7 Tm/A
I, current flowing through wire, measured in amperes
B, magnetic field strength, measured in Tesla
R, distance from wire, measured in meters
An electromagnet is a piece of wire intended to generate a magnetic field with passage of electric current through it. Though all current-carrying conductors produce magnetic fields, an electromagnet is constructed in such a way as to maximize strength of magnetic field it produces for a special purpose. As electrically-controllable magnet, electromagnets form part of a wide variety of ‘electromechanical’ devices: machines which produce a mechanical force through electrical power.