Think half marks is a worst scenario guess. It was a really difficult paper 1- one of the most difficult compared to past papers imo? 1-2 marker Q's were good and the 6 marker Q turned out not horrid, but tons of dumb mistakes on almost all 3-4 markers like mass of the arrow on the bow&arrow Q I'd say. Icing on the cake was defo the waves question, probably lucky to get 1 mark on that refractive index one. I got the answer to be around 2.4 but looking back now with a slightly different method maybe around 1.4?
Feel a bit disheartened, hoping paper 2 will make up for it