Orange County’s jobless rate jumped to 4.1%.

The continuing slump in the electronics industry, as well as normal seasonal factors, caused the number of jobs available at Orange County firms to plunge by 11,900 between December and January. The county’s January jobless rate climbed nearly half a point from December’s 3.7%. The January rate matched that of Marin County as the second lowest in the state, behind the 4% rates for San Mateo and Alpine counties. Los Angeles County posted a 5.6% jobless rate; the California rate was 6.2% and the national figure was 6.7%.