A rod PQ of length 2 m rotates about P at 4 rad s⁻¹ perpendicular to uniform magnetic field B₀. At the midpoint, electrostatic field magnitude is E = xB₀. Determine x.
Physics · Mixed Chapter
JEE Main Practice

Question

A rod PQ of length 2 m rotates about P at 4 rad s⁻¹ perpendicular to uniform magnetic field B₀. At the midpoint, electrostatic field magnitude is E = xB₀. Determine x.

G1 Physics · Accepted Answer

Step 1 — Radius of midpoint is r = L/2 = 1 m. Step 2 — Linear speed of that point is v = ωr = 4 × 1 = 4 m s⁻¹. Step 3 — In steady motional equilibrium, eE = evB₀, hence E = vB₀ = 4B₀. Step 4 — x = 4.