A long straight wire carries a current of `35A`. What is the magnitude of the field `vecB` at a point `20cm` from the wire?

Explanation

Current in the wire, `I = 35A`
Distance of a point from the wire, `r = 20 cm = 0.2m`
Magnitude of the magnetic field at this point is given as:
`B = (mu_(0))/(4pi) (2I)/(r)`
Where,
`mu_(0) =` Permeability of free space `= 4n xx 10^(-7) TmA^(-1)`
`B = (4pi xx 10^(-7) xx 2 xx 35)/(4pi xx 0.2)`
`= 3.5 xx 10^(-5)T`
Hence, the magnitude of the magnetic field at a point 20 cm from the wire is `3.5 xx 10^(-5)T`.