In vechicles ac current is generated and they are used for lightining and other purposes. From the dynamo one wire is taken and given to thebulbsand the other end of the other end is connected to the body of the vechicle. My doubt is that won't the resistance of the body of the vechicle include in the circiut. The body of the vechicle is made up of steel or some metal other than copper. Hence their resistance is more.