Question

Consider a solenoid that is 50 cm long and has a cross-sectional area of 5 cm2. It is wound with 400 turns of wire, and a current of 2.3 A is supplied to it. Assume that its core has a relative permeability of 400. How much flux is in the solenoid?

Answer 1

The magnetic field inside a solenoid

$$B=\mu n I=k\mu_0\frac{N}{L}I$$

$$B=400*4\pi*10^{-7}*\frac{400}{0.5}*2.3=0.924\:\rm T$$

The magnetic flux

$$\Phi=BA\\ =0.924*5*10^{-4}=4.6*10^{-4}\:\rm Wb$$