Home › ISC Class 12 › Physics › Moving Charges and Magnetism › The proportionality constant μ₀/4π in the Biot–S…
The proportionality constant μ₀/4π in the Biot–Savart law has the exact SI value:
A9 × 10⁹ T m A⁻¹
B10⁷ T m A⁻¹
C4π × 10⁻⁷ T m A⁻¹
D10⁻⁷ T m A⁻¹
Answer & Solution
Correct answer: D. 10⁻⁷ T m A⁻¹
1. The permeability of free space is $\mu_0 = 4\pi \times 10^{-7}$ T m A⁻¹.
2. The Biot–Savart constant is $\dfrac{\mu_0}{4\pi}$.
3. Dividing: $\dfrac{4\pi\times10^{-7}}{4\pi} = 10^{-7}$ T m A⁻¹.
4. The $4\pi\times10^{-7}$ option is $\mu_0$ itself, not $\mu_0/4\pi$.
_Source: NCERT Class 12 Physics Ch 4 "Moving Charges and Magnetism", p.144_
Related questions
An electron and a proton enter a magnetic field with the same kinetic energy, perpendiculaA galvanometer is converted into an ammeter of higher range by connecting:The work done by a static magnetic force on a moving charge is:Magnetic field at a point on the axis of a circular loop, far from the loop (distance x ≫ The dimensional formula of the magnetic field B (in SI units of tesla) is:A cyclotron of magnetic field B accelerates positive charges of mass m, charge q. The cyclTorque on a magnetic dipole (current loop) of moment m placed in a uniform field B at anglTwo long parallel wires carry currents I₁ and I₂ in the SAME direction, separated by dista