Question

1. A straight wire carries a current of 3 A. Calculate
the magnitude of the magnetic field at a point 10 cm
away from the wire.
​

Answer 1

⇒ Given:

A straight wire carries a current of 3 A. [3 ampere]

⇒ To Find

The magnitude of the magnetic field at a point 10 cm away from the wire.

⇒ Formula to be used:

Ampere's Circuital Law:

$\sf{\dfrac{\mu_{o}I}{2\pi\:d}}$

⇒ Solution:

Current [I] = 3A

Distance [d] = 10 cm = 0.1 m

Substituting the required values in the equation:

$\sf{=\dfrac{4\pi\times10^{-7}\times3}{2\pi\times0.1}}$

$\sf=\dfrac{6\times10^-7}{10^{-1}}$

$\sf{=6\times10^{-6}}$

Hence the magnitude of the magnetic field is 6 x 10-⁶ T.

Knowledge Bytes:

→ Ampere's Circuital Law

Ampere's circuital law which came into existence in the year 1826 helps us to measure the magnitude of the magnetic field of an electric current.

$\sf{\dfrac{\mu_{0}I}{2\pi\:d}}$

Here:

μ0 = Permeability of the vacuum

I = Current

d = Distance in m

The magnitude is expressed as B.

The SI unit of magnetic field is Tesla denoted by the capital letter T.

→ Magnetic property of electric current

It is scientifically proven that a wire carrying electric charges has its own magnetic field. When a compass is brought near such a wire, it deflects from its usual north - south direction.