If you increase the probe size from 0.003 to 0.006, the heat pattern gets smaller.

• A. It gets larger
• B. It remains the same
• C. It gets smaller
• D. It becomes erratic

Answer: (C)

The size of the heat pattern is governed by how energy is concentrated in the tissue. When you increase the probe size, the contact area with the tissue becomes larger, so the current is spread over a bigger area. With the same amount of current, this lowers the current density at any given point, which reduces how intensely the tissue heats in a localized spot. As a result, the region that reaches a noticeable temperature shrinks, making the visible heat pattern smaller.

In short, bigger probe means energy is more diffused and the heated area is less pronounced, so the heat pattern appears smaller.