Question

Transcranial magnetic stimulation (TMS) is a noninvasive technique used to stimulate regions of the human brain. A small coil is placed on the scalp, and a brief burst of current in the coil produces a rapidly changing magnetic field inside the brain. The induced emf can be sufficient to stimulate neuronal activity. One such device generates a magnetic field within the brain that rises from zero to 1.5 T in 120 ms. Determine the induced emf within a circle of tissue of radius 1.6 mm and that is perpendicular to the direction of the field.

Answer 1

0.125 volts

Step-by-step explanation:

The induced emf can be sufficient to stimulate neuronal activity.

One such device generates a magnetic field within the brain that rises from zero to 1.5 T in 120 ms.

We need to find the induced emf within a circle of tissue of radius 1.6 mm and that is perpendicular to the direction of the field. The formula for the induced emf is given by :

`\epsilon=-(d\phi)/(dt)`

Where

`\phi` is magnetic flux

So,

`\epsilon=-(d(BA))/(dt)\\\\=2\pi r* (dB)/(dt)\\\\=2\pi * 1.6* 10^(-3)* (1.5-0)/(120* 10^(-3))\\\\=0.125\ V`

So, the induced emf is equal to 0.125 volts.