Question

give a formula which relates magnetic pole strength with area of cross-section

Answer 1

As the length of the coil is approximately L=N(2πr), where N is the number of turns and r is the radius of the circumference of each turn, and the area is A=πr^2, we can represent length in terms of area: L=N(2√π)(√A) Hence: L∝A^(1/2) Therefore, as we said that magnetic field strength, B, is directly proportional to the firs power of L, we can also say that: B∝A^(1/2) Thank you,
Hope it help u///