I've been helping my son prepare for a Physics exam and have been going through past and practice papers with him. I have noticed a few mistakes (wrong answers/more than one correct answer) in the practice papers, but I wasn't quite so sure about the one below - sorry for poor quality phone photo. I couldn't think how to do it (mind you it was 1969 when I passed my Higher Physics!) so maybe I'm missing something. It seems to be missing a value - battery voltage would be the obvious one to me. Is it actually possible to answer it? (It's only worth 1 mark out of 110). TIA for comments.