Which of the following statements are true regarding Biot – Savart’s law?

(i) According to biot – savart’s law magnetic field is directly proportional to the length of the element.

(ii) Biot – Savart’s law deals with electric field.

(iii) Magnetic field is directly proportional to current through the conductor.

CONCEPT:

• Biot-Savarts Law: The law that gives the magnetic field generated by a constant electric current is Biot-savarts law.
• Let us take a current-carrying wire of current I and we need to find the magnetic field at a distance r from the wire then it is given by:

\(dB = \;\frac{{{\mu _0}\;I}}{{4\pi }}\left( {\frac{{\overrightarrow {dl} \times \hat r}}{{{r^2}}}} \right)\)

Where μ0= 4π × 10-7 T.m/A is the permeability of free space/vacuum, dl = small element of wire and r ̂ is the unit position vector of the point where we need to find the magnetic field.

EXPLANATION:

From the above expression of the Biot-savart law, the magnetic field is: 

• Directly proportional to the length of the wire. So statement (i) is correct.
• Directly proportional to the electric current. So statement (iii) is correct.
• Biot-savart law gives the magnetic field, not the electric field. So statement (ii) is wrong.