For 6 markers:
Jan 12 - Electricity
June 12- Electricity (Oscilloscopes)
Jan 13 - Electricity
June 13 - Particles (Hadrons and leptons)
My guess is that it could be on quantum phenomena for example line spectra or the photoelectric effect (this is based on the last 4 past papers)
However darned AQA could throw in yet another boring old elec one, who knows...