Physicshard · Past Paper
A solenoid of length 0.5m has 500 turns. If 2A current flows, calculate the magnetic field strength (take μ₀ = 4π x 10^-7 T m/A).
A4π x 10^-4 T
B8π x 10^-4 T
C2π x 10^-4 T
D1.25 x 10^-3 T
✓ Correct Answer: B — 8π x 10^-4 T
B = μ₀ * (N/L) * I = (4π x 10^-7) * (500/0.5) * 2 = 4π * 10^-7 * 1000 * 2 = 8π * 10^-4 T.
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