A dry human body typically has a much higher electrical resistance than a wet one because water is a good conductor of electricity due to the presence of ions, while dry skin is a relatively poor conductor.

• Presence of Ions in Water:

  Water, especially when it contains impurities like salts and minerals (as is the case with sweat or tap water), dissociates into ions (charged particles). These ions act as charge carriers, facilitating the flow of electric current. USGS Water Science School

• Dry Skin as an Insulator:

  Dry skin is primarily composed of dead cells that lack free ions or electrons to carry current effectively. The outermost layer of the skin, the stratum corneum, is particularly dry and acts as an insulator.

• Effect of Moisture:

  When the skin is wet, water penetrates the outer layers, introducing ions that drastically reduce the skin's resistance. This allows electricity to flow more easily through the body.

• Resistance Values:

  Dry skin can have a resistance of hundreds of thousands of ohms or even megohms. Wet skin, however, can have a resistance as low as a few thousand ohms or even less.

In summary, the presence of ions in water significantly enhances its conductivity, making a wet body far less resistant to electrical current than a dry body.