Attraction of water droplet to my finger?

In summary: The jumping of water droplets onto a dry finger after rain is caused by adhesion, specifically induced dipole interactions between the negatively charged oxygen end of water molecules and the positively charged finger. This effect may be enhanced if the finger is slightly damp or sweaty, due to the presence of ionic compounds in sweat. In summary, the jumping of water droplets onto a dry finger after rain is due to adhesion and induced dipole interactions, potentially augmented by the presence of ionic compounds in sweat.
  • #1
pivoxa15
2,255
1
After a rain, when there are tiny water droplets hanging down from places, I can put my dry finger near one of the droplets and if my finger is close enough to the droplet, it will jump onto my finger. Just like a metal jumping onto a magnet.

What physical explanation could be given here? Is it simply the negative ends of all the water molecules in the droplet attracted to my positively induced finger?
 
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  • #2
  • #3
i think you hit it, negative polarity on the oxygen end of water attracts to your positively charged finger.

if you're finger was slightly wet though it would have been due partly to the polarity of the molecules and partly due to hydrogen bonding
 
  • #4
rctrackstar2007 said:
i think you hit it, negative polarity on the oxygen end of water attracts to your positively charged finger.

if you're finger was slightly wet though it would have been due partly to the polarity of the molecules and partly due to hydrogen bonding

This is indeed a good point, sweat contains not only the polar H2O water molecule, but also ionic compounds, which could contribute to the effect. If your finger is damp / sweaty you will have both cohesion and adhesion.

~H
 

1. How does a water droplet stick to my finger?

Water molecules have a property called surface tension, which allows them to stick together and form droplets. When your finger touches the water droplet, the surface tension pulls the water molecules towards your finger, causing it to stick.

2. Why do water droplets form on my finger?

Water droplets form on your finger due to a process called condensation. When the temperature of the surrounding air is lower than the temperature of your finger, the water vapor in the air condenses and forms droplets on the cool surface of your finger.

3. Can I control the attraction of water droplets to my finger?

Yes, you can control the attraction of water droplets to your finger by altering the surface tension. For example, if you rub soap on your finger, it will decrease the surface tension and make it more difficult for water droplets to stick to your finger.

4. Why do some surfaces attract water droplets more than others?

Some surfaces have a higher surface tension than others, which means they are better at pulling water molecules towards them. Additionally, surfaces with a rough or uneven texture provide more surface area for water droplets to adhere to, making them more attractive to droplets.

5. Can the attraction of water droplets to my finger be used for any practical purposes?

Yes, the attraction of water droplets to your finger can be utilized in many practical applications, such as creating self-cleaning surfaces or designing adhesives that work well in wet environments. It can also be used in industries like agriculture and medicine to manipulate the movement of water droplets for specific purposes.

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