Radius of a Raindrop given Charge and Electric Potential

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SUMMARY

The discussion revolves around calculating the radius of a spherical raindrop given its charge of 5×10-6 C and an electric potential of 8.800×10-8 V at the surface. The formula used is V = (kQ)/r, where k is Coulomb's constant. The initial calculation yielded an implausible radius of 5.11×1011 m, prompting participants to suspect a misprint in the potential value or charge, as both appear unusually high for a raindrop.

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  • Understanding of Coulomb's Law and electric potential
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  • Basic knowledge of unit conversions in physics
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freddy13
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Homework Statement


A spherical rain drop carries a charge of 5×10-6 C and has a potential of 8.800×10-8 V at the surface. Find the radius of the drop.


Homework Equations



V = (kQ)/r

The Attempt at a Solution



I simply moved V and r to their respective spots and plugged in my numbers. I got a very large number of 5.11*10^11, so i am wondering if my units are wrong or if I am doing something else wrong. Thanks for your help!
 
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Hello, freddy13.

You're right, you're getting a ridiculous answer even though your method is correct. (Your answer for the radius is more than 3 times the distance to the sun.) The value for the potential looks very suspicious. Are you sure that 10 is raised to the negative 8 power? Also, the value for the charge seems very high for a raindrop.
 
Last edited:
Yeah I copied the problem exactly! It has to be something with the units that I am missing, that seems to be the only possibility!
 
I agree. It must be a misprint in the statement of the problem.
 

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