Magnetoencephalography (meg) is a technique for measuring changes in the magnetic field of the brain caused by external stimuli such as touching the body or viewing images of food. such a change in the field occurs due to electrical activity (current) in the brain. during the process, magnetic sensors are placed on the skin to measure the magnetic field at that location. typical field strengths are a few femtoteslas (1 femtotesla=1 ft=10−15 t) . an adult brain is about 140 mm wide and divided into two sections (called "hemispheres" although the brain is not truly spherical), which are each about 70 mm wide. model the current in one hemisphere as a circular current loop 65.0 mm in diameter. a sensor is placed so that it is along the axis of the loop, 3.10 cm from the center. suppose a magnetic field of 4.95 ft is measured by the sensor. according to the model, what is the current in the hemisphere of the brain being measured?