The answer on the question sheet was "High voltage static electricity", but my answer of "Static electricity" was thankfully accepted.
The voltage generated obviously depends on the size of the machine, but one posting on this forum says that "school models tend to be unimpressive next to van der graaf machines, 75kv versus 250kv." It would therefore seem harsh, to say the least, to insist that the answer must include the words "high voltage".
© Macclesfield Quiz League 2016