Which is NOT a good electrical conductor?

• A. Iron
• B. Saliva
• C. Water
• D. Sweat

Answer: (B)

Electricity flows best where there are plenty of charge carriers. Metals like iron have many free electrons that move easily, so they are excellent conductors. Water conducts when it contains dissolved ions; ordinary water has minerals that provide ions, so it carries current. Sweat contains salts and electrolytes, which supply ions and make it a good conductor. Saliva, while mostly water, has relatively few ions, so it provides fewer charge carriers and conducts electricity less well than the others. That’s why saliva isn’t a good electrical conductor compared with iron, water, or sweat.