Chapter 27, Problem 27.85PP

The large magnetic fields used in MRI can produce forces on electric currents within the human body. This effect has been proposed as a possible method for imaging “biocurrents” flowing in the body, such as the current that flows in individual nerves. For a magnetic field strength of 2 T, estimate the magnitude of the maximum force on a 1-mm-long segment of a single cylindrical nerve that has a diameter of 1.5 mm. Assume that the entire nerve carries a current due to an applied voltage of 100 mV (that to a typical action potential). The resistivity of the nerve is 0.6 Ω · m. (a) 6 × 10⁻⁷ N; (b) 1 × 10⁻⁶ N; (c) 3 × I0⁻⁴ N; (d) 0.3 N.