Atoroid filled with a magnetic substance carries a steady current of 1.9 a. the coil contains 1200 turns, has an average radius of 3.86 cm. the magnetic field through the toroid is 0.289683 t. assume the flux density is constant. what is the magnetic field strength h within the core in the absence of the magnetic substance? answer in units of a/m. 013 (part 2 of 2)
determine the permeability of the core material. answer in units of wb/a m.

The answer is orbit around nucleus

You would need to take a picture so i can see

Ohm's law tells you that i = v/r where v is equivalent voltage and r is equivalent resistance of the circuit
since all circuits have the same voltage, your question is really asking which circuit has the lowest total resistance, since the lower the resistance, the higher the current
circuit a has a resistance of 5 ohms; circuit c is in series so has a resistance of 10 ohms; circuit b is in parallel and therefore has a resistance of 2.5 ohms (review your notes on adding resistances in parallel and series); therefore b has the highest current

Work is reduced while time is decreased