(b) (5%) Find out the shortest short-circuited stub length Is required to match the load at interface BB'.

3. A long straight conducting wire has a circular cross-section of radius R and carries a current I. Inside the conductor, there is a cylindrical hole of radius a whose axis is parallel to the axis of the conducting wire and is Iocated at a distance b from it. Calculated the magnetic field inside the hole. (15 pts).