Determine the magnetic flux density, B, inside an ideal solenoid of length much greater than diameter. The current in the wire is io and n is the number of turns per unit length.

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1. For the magnetic circuit given below, the distances constituting the mean core path are given in 'k'. There are three coils on the magnetic core. The magnitudes and the directions of the coil currents are given in T'. Cross-sectional area and magnetic permeability of the core are constant and uniform. Number of turns for the coils ('N') are the same. 41, d2 and d3 are the fluxes generated by currents I,, Iz and I3, respectively. a. Sketch the magnetic equivalent circuit of the core. b. Give the parametrical expression for reluctances. c. Give the parametrical expression for coil MMFS (Amper-Turn). d. Calculate the following ratios; $1/ P2 = ? $2/ P3 = ? P1/ 03 = ? t: Please mind the winding and current directions for flux calculations. k/2 k/2 b/4 N N F1 F2

Example 1.2 An electromagnet has an air gap of 4 mm and flux density in the gap is 1-3 Wb/m?. Determine the ampere-turns for the gap.

2.3

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A ten-turn solenoid has a ferromagnetic core with a relative permeability of 10,000. The length of the solenoid is l=10 cm and its cross section area is A=1 cm2.  The amount of current driving the solenoid is 0.1 A.  Determine the magnetic flux intensity H in the core. Provide your answer in A/m.  Round off to your answer to one decimal.