In the diagram of TMS shown in Figure 21.70, a current pulse...

In the diagram of TMS shown in Figure $21.70,$ a current pulse increases to a peak and then decreases to zero in the direction shown in the stimulating coil. What will be the direction $(1$ or 2$)$ of the induced current (dotted line) in the brain tissue? A. 1 B. 2 C. 1 while the current increases in the stimulating coil and 2 while the current decreases D. 2 while the current increases in the stimulating coil, 1 while the current decreases

In the diagram of TMS shown in Figure $21.70,$ a current pulse increases to a peak and then decreases to zero in the direction shown in the stimulating coil. What will be the direction $(1$ or 2$)$ of the induced current (dotted line) in the brain tissue?
A. 1 B. 2
C. 1 while the current increases in the stimulating coil and 2 while the current decreases
D. 2 while the current increases in the stimulating coil, 1 while the current decreases

Key Concepts

Faraday's Law of Electromagnetic Induction

This principle explains that a changing magnetic field produces an electric field, which in turn induces a current in a nearby conductor. It is the foundational law that describes how time-varying magnetic fields can create electrical currents without direct electrical contact.

Lenz's Law

Lenz's Law states that the direction of the induced current is such that its own magnetic field opposes the change in the original magnetic flux. This concept is critical for understanding why induced currents in systems like TMS reverse direction when the primary current's rate of change alters.

Transcranial Magnetic Stimulation (TMS)

TMS is a non-invasive method that uses magnetic fields to induce electric currents in the brain, thereby modulating neural activity. The technique relies on the principles of electromagnetic induction and the precise control of current pulses to achieve therapeutic or diagnostic effects in neural tissue.

Time-Varying Magnetic Fields

The variation in magnetic field strength over time is key to inducing electric fields and currents in conductive materials. Understanding how these fields change and interact with conductive tissue underpins the application of techniques like TMS and explains the behavior of induced currents.

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