Whoa, I messed up on the capacitors question too!
I got 9.2A for the current, 158g for the wooden block and 0.223 m/s (too many s.f.?) for the speed of the water wave.
Looking at the numbers in this thread, I was wondering whether Edexcel specifies a set weight for the wooden block, or whether schools just use any they like and write the weight on the front of the paper?
My k value was around 7.9, and my uncertainty in d was around 16%, so I wrote that there must have been a systematic error in my experiment lol (no idea what it was though).
But on the whole the paper went ok, I did better than I expected.