Question:
Coercivity \(=4\times10^3 A/m\). Solenoid: 500 turns, length 1 m. Find current needed to demagnetise.
Coercivity \(=4\times10^3 A/m\). Solenoid: 500 turns, length 1 m. Find current needed to demagnetise.
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For solenoid: \(H = NI/L\), not \(\mu_0 NI/L\).
Updated On: Apr 23, 2026
- \(2.5A\)
- \(5A\)
- \(8A\)
- \(10A\)
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The Correct Option is C
Solution and Explanation
Concept:
Magnetic field in solenoid:
\[
H = \frac{NI}{L}
\]
Step 1: Use coercivity
\[ H = 4\times10^3 = \frac{500 \cdot I}{1} \]
Step 2: Solve
\[ I = \frac{4\times10^3}{500} = 8A \] Conclusion: \[ 8A \]
Step 1: Use coercivity
\[ H = 4\times10^3 = \frac{500 \cdot I}{1} \]
Step 2: Solve
\[ I = \frac{4\times10^3}{500} = 8A \] Conclusion: \[ 8A \]
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