Transcranial magnetic stimulation(TMS) is a noninvasive method for studying brian function, ans possibly for treatments as well. In this technique, a conducting loop is held near a persons head. When the current in the loop is changed rapidly, the magnetic field it creates can change at the rate of 3.00x10^4T/s. This rapidly changing magnetic field induces an electric current in restricted region of the brain that cause a finger to twitch, bright spots to apprear in the visual sphere or feeling of complete happiness to overwhelm a person. If the magnetic field changes at the previous mentioned rate over an are 1.13x10^-2m^2, what is the induced emf? (answer is 339V)
Explanation / Answer
rate of change of magnetic field dB / dt = 3 * 10 4 T / s Area A = 1.13 * 10 -2 m 2 Induced emf E = d / dt where = magnetic flux = BA = A dB / dt = 339 Volt