Please solve complete problem. I need complete step by step solution. Course: Electromagnetic theory

An infinitely long coaxial axis as in the figure with inner radius a and outer radius b. The inside of the transmission line is filled with a dielectric material with Er = 9 and mr = 1. This transmission electric field intensity of the wave formed between the plates of the line 100 E = ar cos (108t - Bz) are given as. (Herer represents the distance from the center according to the cylindrical coordinates.) Find B accordingly. b .......... Er=9, Wr=1