It's your body's way of cleaning and protecting the vagina. For instance, it's normal for discharge to increase with sexual arousal and ovulation. Exercise, use of birth control pills, and emotional stress may also result in discharge. Abnormal vaginal discharge, however, is usually caused by an infection. or Electric discharges can convey substantial energy to the electrodes at the ends of the discharge. A spark gap is used in internal combustion engines to ignite the fuel/air mixture on every power stroke. Spark gaps are also used to switch heavy currents in a Marx generator and to protect electrical apparatus.