A conducting sphere of radius 2.0 cm has an excess charge of 10 nC on it. A seco

Question

A conducting sphere of radius 2.0 cm has an excess charge of 10 nC on it. A second conducting sphere of radius 4.0 cm has an excess charge of 2.0 nC on it.

a. Conceptual Question: If the two spheres are placed next to each other, which will have a larger force exerted on it? Please explain detail of the physics involved.

b. Calculation Question: The two spheres are brought into contact and then placed 10cm apart (surface to surface). What is the magnitude of the force exerted on the second sphere? Please show your work using the appropriate given equations.

c. Conceptual Question: Will the spheres be attracted to or repelled from each other after they are brought into contact? Please explain detail of the physics involved.

Given Possible Equations to be Used:

*Coulomb's Law (magnitude of electric force) F = k|q1q2|/r2

*Magnitude of electric field from point charge E=k|Q|/r2

*Force on point charge F = q E

*Kinematics equations v(t)=v0+at

x(t) = x0 + v0t + 1/2at^2

*Electric potential due to a point charge V=kQ/r

*Electric potential difference between points V = Es

in a uniform field (remeber that s is displacement in the direction of the field)

*Electric potential energy of a point charge PE = qV

Explanation / Answer

a. The charges exert forces on each other equal in magnitude and opposite in direction. As the force is due to both charges. single charge can't attract without other one.

b. when two spheres are in contact then their charges becomes equal and both will have 10-2 = +8nC charges

Repulsion Force between them after 10 cm distance = kQ2 /r2

= 9x10^9* (8x10^-6)2/0.12 =57.6 N..............Ans.

c. they will repelled each other. as they have same positive charges.

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