If the distance between the electrodes is far apart, the stimulation tends to be:

• A. Deeper and Weaker
• B. Shallower and Stronger
• C. Unchanged Depth
• D. Increased Heat

Answer: (A)

Spacing between the electrodes controls where the electric field is strongest and how concentrated the current is at the surface versus deeper tissues. When the electrodes are far apart, the current path must pass through more tissue and the field becomes more spread out. This lowers the current density under any single surface point, so the sensation at the skin is weaker, but the electric field penetrates deeper, producing stimulation in deeper tissues. If the electrodes are placed close together, the current density is higher near the surface, giving stronger, more superficial stimulation. Increased heat tends to come with high surface current density, which is less with wide spacing.