The location of the protoncan be expressed as:
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The location of the electron can be expressed as:

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Hence, the position vector can be expressed as:
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The distance of the particle is expressed as:

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a) From the coulomb’s law, the force exerted by the proton on the alpha particle is expressed as:
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Here, F is the force exerted by the proton,
is the charges of the proton and the alpha particle which are
respectively, k is the coulomb’s constant that is
and r is the distance amongst the particles that is 
Substituting the values in the above equation, we get-

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Thus, the force the proton exerts on the alpha particle is 
b) From the coulomb’s law, the force exerted by the alpha particle on the proton is expressed as:
![]()

Here, F is the force exerted by the proton,
is the charges of the proton and the alpha particle which are
respectively , k is the coulomb’s constant that is
and r is the distance amongst the particles that is 
Substituting the values in the above equation, we get-
![]()

Thus, the force the alpha particle exerts on the proton is