Given, relative permeability,
µr=501 Current through solenoid,
I=2.5A and number of turns per unit length,
n=‌=900 As we know that,
B=µ0H ⇒‌‌H=‌ where,
B= magnetic flux density / magnetic induction,
µ0= free space permeability
and
H= magnetising field intensity.
Since, magnetic field due to solenoid,
B=µ0nI Here,
µ is permeability of medium
and
µ=µrµ0 where,
µr is relative permeability.
∴‌‌H‌‌=‌=‌ ‌‌=‌ ⇒‌‌H‌‌=nµrI ‌‌=900×501×2.5 ‌‌=1.12×106A∕m