Practice question

**SI unit of magnetic field** is tesla (T), defined as force 1 N on 1 A·m wire perpendicular to field. Moving coil galvanometer uses torque τ = N I A B balanced by spring torque k φ, so deflection φ ∝ I, enabling current measurement, with radial field ensuring τ = N I A B always maximum. The torque on a current-carrying loop in a magnetic field is given by tau = N I A B sin θ . It is maximum when sin θ = 1 , i.e., θ = 90° , meaning the plane of the loop is perpendicular to the magnetic field.