A Piper PA-38-112 collided with an unmarked power transmission line static cable during the takeoff climb after executing a touch and go maneuver. The airplane was at a constant airspeed and low altitude above the upsloping terrain located north of the airport. The airplane then struck the static cable with its right wing as it entered a right turn. The 20:1 approach clear zone plane ratio for the departure end of the runway is obstructed by an approximate four foot high dirt berm. Rising terrain continues north of the airport but does not obstruct the 20:1 clearance ratio. Power transmission lines cross Runway 33's extended centerline on a northwesterly heading about 3,800 feet from the runway end. Support towers for the power transmission line cables are about 60 feet above ground level, but did not extend into the 20:1 clearance ratio. The power transmission lines are depicted on the sectional aeronautical chart. The airplane's flaps were found to be fully extended. The Piper information manual does not prescribe the use of full flaps for any takeoff maneuvers.