Errors & Misconceptions in MAG-01

Magnetic force does work: FALSE. F = qv×B is always perpendicular to v, so work = F·v dt = 0. Speed and kinetic energy are unchanged; only direction changes.
Faster particle → shorter period in B: FALSE. T = 2π $\frac{m}{qB}$ — no velocity term. Faster → larger radius → longer circumference; these cancel exactly, giving the same period.
Voltmeter needs high resistance in parallel: FALSE. A voltmeter needs high resistance in SERIES. Parallel connection would short-circuit and draw massive current.
Ammeter needs low resistance in series: FALSE. An ammeter needs low resistance in PARALLEL (shunt). Series placement of low resistance would reduce circuit current.
Solenoid $B \propto total$ turns N: FALSE. B = μ_{0}nI where n = $\frac{N}{L}$ . If length doubles with same N, n halves and B halves. It is turns per unit length that matter.
Diamagnetic χ > 0: FALSE. Diamagnetic: χ < 0 (repelled). Paramagnetic: χ > 0 small. The sign of χ determines behaviour.
Retentivity = Coercivity: FALSE. Retentivity is residual B when H = 0 (y-intercept). Coercivity is reverse H to make B = 0 (x-intercept). These are distinct material properties.
Magnetic field lines can start and end like electric field lines: FALSE. B field lines are always closed loops (no magnetic monopoles); ∮B·dA = 0.
Toroid has no field in the hollow centre: TRUE, but also zero outside the toroid. Students often forget B = 0 BOTH in the central hole and in the exterior region.
Curie's law χ = $\frac{C}{T}$ applies to ferromagnets: FALSE. Curie's law is for paramagnets. Ferromagnets above Curie temperature follow the Curie-Weiss law χ = $\frac{C}{T − T_C}$ .