\({\mu _r} = (1 + {\chi _m})\) \(==>\) \({\mu _r} = \frac{B}{{{\mu _0}H}} = \frac{\phi }{{{\mu _0}HA}}\)
\({\mu _r} = \frac{{2.4 \times {{10}^{ - 5}}}}{{(4\pi \times {{10}^{ - 7}}) \times 1600 \times (0.2 \times {{10}^{ - 4}})}}\) \(= 596.8. \)
\({\chi _m} = 595.8 \approx 596\)