Medical devices implanted inside the body are often powered using transcutaneous energy transfer (tet), a type of wireless charging using a pair of closely spaced coils. an emf is generated around a coil inside the body by varying the current through a nearby coil outside the body, producing a changing magnetic flux. calculate the average induced emf (in v) if each 15.0-turn coil has a radius of 1.80 cm and the current in the external coil varies from its maximum value of 11.5 a to zero in 6.75 ✕ 10−6 s. (hint: recall from topic 19 that the magnetic field at the center of the current-carrying external coil is