Bending water - static attraction

13 March 2011

Ingredients

A tap A balloon

Instructions

This works best on a dry day.

Set the tap running gently so that it has a stream of water coming out. Move the inflated balloon near to the stream of water.

Rub the balloon on your hair.

Now move the balloon near the stream of water.

Result

You should find that the uncharged balloon doesn't affect the stream of water but once you have rubbed it on your head the water is attracted, and attracted more the closer you move the balloon.

Explanation

When you rub the balloon you touch the balloon to your hairs. when this happens a few electrons are transferred from the hair to the balloon. Rubbing repeats this millions of times, leaving the balloon charged.

The water starts off neutral, with the same amount of positive and negative charges. When you bring the charged balloon near to the water it pushes electrons away, leaving a positively charged area which is attracted to the balloon.

Water coming out of the tap in a stream Charged balloon near water stream Bending water stream
The water coming from the tap is neutral with positive and negative charges. The negatively charged balloon pushes electrons away from the stream of water nearest the balloon, leaving this area slightly positive. This positively charged water is attracted to the balloon so the stream is deflected.

A similar effect is used in spray painting, the spray is charged in one direction and the object to be painted is charged the other way, so the paint is attracted to the object, and can even paint the back.

Comments

But the negative ions are pushed away and the positve charges are pulled to the baloon. So, like in a capacitor there is a charge separation. But I dont understand how there is a net movemnt of the whole stream.
My hypothasis is that the friction between the water and the pipe caused to the water to be positivly charged, and thus to attract to the negative baloon.

Because the positive charges are closer to the baloon than the negative ones

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