Hi,
Known -
L=5 cm, N=200 turns, µr=300, µo=4π×10(-7)H/m, d=1mm=1×10(-3)m
A=πD²/4=7.85×10(-7)m²
Unknown -
flux density--->B=?
current--->I=?
Formulae -
Φ=BA; Φ=NI/R ;R=L/µA (reluctance);(Φ-magnetic flux);
By substitution-
BA=NI/R
B=µNI/L
B=µoµrNI/L= 1.501×I Tesla
substitute the numerical value of I to get the answer.
Regards
∞