Ampere’s Law Formula and Example

Ampere’s Law Formula :

Ampere’s Law formula  B(N/m) in Newton per meter and multiply the dl is equal to the μ0(N/A2)   in Newton per Ampere and multiply the  current flowing through the closed loop I(amp) in ampere. Hence the Ampere’s Law formula can be written as,

∮B(N/m) *dl=μ0(N/A2)  * I(amp)

Natation’s used in Ampere’s Law Formula

B →magnetic field in N/m

L → infinitesimal length in m

I → current flowing through the closed-loop in amp

μ→ e permeability in N/A2

Example 1:

Calculate the magnetic field of a long straight wire that has a circular loop with a radius of 0.08m. 4amp is the reading of the current flowing through this closed loop.

Solution :

Given,

R=0.08m

I=4amp

μ0 = 4π×10-7N/A2

Ampere’s law formula is

∮B dl=μ0 I

In the case of long straight wire

∮ dl =2π R

=2 ×3.14×0.08

=0.5024

B∮ dl= μ0 I

B= μ0 I /2π R

B=4 π ×10-7 ×4 /0.5024

=0.507×10-7 T

Example 2:

Calculate the magnetic field of a long straight wire that has a circular loop with a radius of 0.05m. 2amp is the reading of the current flowing through this closed loop.

Solution :

Given,

R=0.05m

I=2amp

μ0 = 4π×10-7N/A2

Ampere’s law formula is

∮B dl=μ0 I

In the case of long straight wire

∮ dl =2π R

=2 ×3.14×0.05

=0.314

B∮ dl= μ0 I

B= μ0 I /2π R

B=4 π ×10-7 ×2 /0.314

=8×10-6 T

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