Physics

Physics

Problem

A rectangular loop of area 0.04 m20.04\,\text{m}^2 is kept in a uniform magnetic field of 0.5 T0.5\,\text{T}. At which of the following angles between the magnetic field and the plane of the loop will the magnetic flux through the loop be zero? a) 90∘90^{\circ} b) 180∘180^{\circ} c) 0∘0^{\circ} d) 60∘60^{\circ}
Intuitive explanation

The key is understanding what "angle with the plane" means for flux. Magnetic flux depends on the component of B⃗\vec{B} perpendicular to the loop's surface—that's what actually "threads through" it. When the problem gives an angle measured from the plane itself (not the normal), you need to mentally rotate your perspective: an angle of 0° with the plane means the field lies flat in the plane, so zero perpendicular component and zero flux. The angle that matters for flux is always measured from the normal to the surface.

Intuitive explanation

The key is understanding what "angle with the plane" means for flux. Magnetic flux depends on the component of B⃗\vec{B} perpendicular to the loop's surface—that's what actually "threads through" it. When the problem gives an angle measured from the plane itself (not the normal), you need to mentally rotate your perspective: an angle of 0° with the plane means the field lies flat in the plane, so zero perpendicular component and zero flux. The angle that matters for flux is always measured from the normal to the surface.

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