Lmao I also just did the same nsg 2020 phys trial
For the first graph, the flux through the whole thing is nothing at the start because it’s all parallel to the magnetic field, so effectively no area is in the magnetic field. Then, as it turns more area is in the magnetic field until it peaks when it’s perpendicular. After this, the area is reduced until parallel again, and then repeats the pattern but in the negative direction just because the coil is facing the opposite direction.
For the second graph, in the first bit it experiences a constant amount of force as it is is a current carrying conductor in a uniform magnetic field. But because of the split ring commutator, when it has turned 90 degrees the current switches direction and so the force does too, and then when it’s rotated 270 degrees it switches back.
