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a van de graaff generator causes a total charge q to build up on a metal sphere of radius r. which variable does not affect the electric field at a distance r from the center of the metal sphere? assume r> r.

the distance r from the center of the metal sphere
the magnitude of the charge q
the radius r of the metal sphere
the sign of the charge q

The radius r of the metal sphere

Explanation:

Electric field, where Q is the magnitude of the charge, R is the distance from the center of the metal sphere. Whenever the sign of the charge changes, the direction of electric field also changes. Therefore, it's only the the radius r of the metal sphere does not affect the electric field at a distance R from the center of the metal sphere when R>r

28. evolution

29. environment, survive, offspring  

explanation: