Straight Wire Magnetic Field Formula
A long straight wire carrying a current has a magnetic field due to moving charges which will depend on the right-hand rule. For the case of a long straight wire carrying a current I, the magnetic field lines wrap around the wire and depends on the distance to the wire.
Magnetic field = magnetic permeability * current / (2 π distance from the wire)
The equation is:
B = μ I /2 π r
B: magnetic field
I: current intensity flowing in the cable
r: distance to the wire (perpendicular to the wire)
Straight wire Formula Questions:
1) A wire of 30 cm length carries a current I= 2 A. what is the magnetic field at 50 cm from the wire?
From the formula of the magnetic field of the straight we substitute the values,
B = μ I/2 π r = 4π *10(-7) T*m/A * 2 A /(2 π *0.5 m)
= 8 *10(-7) T
2) A wire of 30 cm length carries a current I= 2 A. At which distance is the magnetic field is of 4*10(-3) T?
From the formula of the magnetic field of the wire we find the distance r,
r= μ I/2 π B = (4π *10(-7) T*m/A* 2A)/(2 π 4*10(-3)T)
r= 0.5 *10(-4) m = 0.05 mm