The answer is nuclear energy
2.83 days into hours = 2.83 x 24 = 67.92 hours
67.92 hours into minute = 67.92 x 60 = 4075.2 minutes
4075.2 minutes into seconds = 4075.2 x 60 = 244,512 seconds.
I believe the most appropriate answer would be to change the core from wood to iron. This is because iron is a magnetic material while wood is not magnetic hence cant acquire magnetism. Other factors that would increase the strength of electromagnet would be; increasing the amount of electric current, and increasing the number of windings.