Two technicians are discussing power locks. technician a states that polarity is switched to the door lock actuators to make them travel both directions. technician b states that door lock actuators are wired with a case ground. which technician is correct?

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.

the part of the wave he is travelling on is the crest