In a bipolar setup, the two electrodes are typically of what size?

• A. Two different sizes
• B. One larger and one smaller
• C. One active and one dispersive
• D. Two equal sizes

Answer: (D)

In a bipolar setup, the current flows directly between two active electrodes. Using two equal-size electrodes ensures the current density is balanced and the field between them is predictable and focused. When both pads are the same size, the impedance at each electrode is similar, so neither electrode concentrates power more than the other, which makes treatment more comfortable and targeted.

If the sizes differed, the smaller electrode would carry a higher current density, causing uneven stimulation and less control over where the effects occur. (In contrast, monopolar configurations use one active electrode with a larger dispersive pad, which changes how the current spreads, not the balanced pair seen in bipolar.) For these reasons, two equal sizes are standard in bipolar setups.