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Physics Dad
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Homework Statement
The Nucleus of a helium ion contains two protons approximately 5x10-15m apart. They can be considered to be surrounded by one orbiting electron approximately 5x10-11m away. Calculate the following:
a) The electrostatic force between the two protons
b) The electrostatic force on the electron caused by the nucleus
c) The electrical potential energy of the electron
Homework Equations
Equations & Values
F=kQq/r2
E=kQ/r2
V=kQ/re=-1.6x10-19C
k=8.99x109Nm2C-2
r (between protons)=5x10-15m
r (electron)=5x10-11m
The Attempt at a Solution
I am confident at my attempt at the answer for part a
F=(8.99x109)(-1.6x10-19)(-1.6x10-19)/(5x10-15)2
F=9.2N (repulsive)
For part b, I am slightly unsure as to what I am doing as I don't particularly understand what is it asking me. As the nucleus has the two protons within it, does this mean that it has double the charge?
e.g. e(nucleus) = 2(-1.6x10-19)C = -3.2x10-19C
so
F=(8.99x109)(-3.2x10-19)(-1.6x10-19)/(5x10-11)2
F=1.8x10-7N (repulsive)
Or am i missing something I should be doing to calculate the charge of the nucleus?
For part C, my immediate thought is that:
V=(8.99x109)(-1.6x10-19)/5x10-11
V=-2.9x10-7V (attractive)
But, given that this answer is worth 3 marks, I am thinking this answer is too simple and I must be missing something here.
I am sorry for this simplistic nature of this question, but in all honesty we have not been told anything on this subject and I am trying to fill in the blanks left by our tutors.
Thank you in advance.
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