Kelvin Water Dropper (Chris Kipp)

Explanation

As water falls into the trash cans, small bits of positive or negative charge can build up on one of the trash cans. It only takes a little bit. If that trash can becomes positive, then the opposite metal can or ring will also become positive. The water falling through that ring will then become induced with the opposite charge and fall into the opposite bucket, giving it the negative charge. That bucket will conduct that charge to the ring above the positive bucket. The water falling through will be induced positive and will fall into the positive bucket, increasing the net positive charge. Eventually, the buckets will become so charged relative to each other that a spark will occur between the hollow spheres.

1. If it takes 3x10⁶Nm/C to ionize air and the spheres are 2cm apart, calculate the amount of electric potential difference generated by this Kelvin Water Dropper.

2. How could you adjust this machine to increase the amount of charge built up between sparks?

3. Why is it important that the two wires connecting the opposite rings be insulated from each other?

Everyday examples of the principles illustrated

spark plugs, electrostatic machines, x-ray machines, microwave oven transformers,

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