An active neurostimulator implant is recharged wirelessly using an external induction coil.
Complete the energy transfer diagram below by identifying the forms of energy at each stage:
Magnetic field energy from the coil⟶[ Energy Form 1 ] energy in the receiver circuit⟶[ Energy Form 2 ] energy in the micro-battery \text{Magnetic field energy from the coil} \longrightarrow [\ \text{Energy Form 1}\ ] \text{ energy in the receiver circuit} \longrightarrow [\ \text{Energy Form 2}\ ] \text{ energy in the micro-battery} Magnetic field energy from the coil⟶[ Energy Form 1 ] energy in the receiver circuit⟶[ Energy Form 2 ] energy in the micro-batteryIt takes 2.4 hours2.4\text{ hours}2.4 hours to fully charge the micro-battery from flat. The average current induced in the charging circuit is 85 mA.
State the equation linking charge, current, and time.
Calculate the amount of charge needed to fully charge the micro-battery, and state the unit.
If the external coil is misaligned with the implant, the electrical power transferred decreases while the induced voltage remains constant. Explain how this misalignment affects the time needed to fully charge the micro-battery.