Time fuzes detonate after a set period of time. Impact, or contact fuzes detonate when they hit something, usually the target. A proximity fuze uses sensors which can be one or more combinations of the following: radar, active sonar, passive acoustic, infrared, magnetic, photoelectric, seismic or even television cameras. Whatever the sensor used, percussion fuzes cause the explosion to occur close to the target. The target will either be destroyed or severely damaged.