【单选题】Two locations in space, A and B, are in a region of uniform electric field E = V/m. Location A is at position m and location B is at position m. What is the potential difference V B -V A ?
【单选题】All items such as steam pipes, exhaust pipes and fittings which, because of their location and operating temperature, present a hazard should be adequately laggedThat means the items should .