Consider the Lincoln Tunnel, which was built in 1939 under the Hudson River in New York. Assume the tunnel to be empty with perfectly conducting walls and rectangular cross section with width 6.55 m and height 4.19 meters. (a) (10%) Find all modes, which propagate at frequency 30 MHz. r(b) (10%) Find phase and group velocities for all propagating modes identified in part (a). Express your results in terms of the speed of light in free space c.