Two small charged spheres, A and B, are placed on insulated stands, 0,2 m apart, as
shown in the diagram below. They carry charges of −4 x 10-6 C and +3 x 10-6 C
respectively.
M is a point that is a distance of 0,1 m to the right of sphere B.
7.1 Calculate the number of electrons in excess on sphere A. (3)
7.2 Calculate the magnitude of the electrostatic force exerted by sphere A on
sphere B. (3)
7.3 Describe the term electric field. (2)
7.4 Calculate the magnitude of the net electric field at point M. (5)
Charged spheres A and B and another charged sphere D are now arranged along a
rectangular system of axes, as shown in the diagram below.
The net electrostatic force experienced by sphere A is 7,69 N in the direction as shown
in the diagram above.
7.5 Is the charge on sphere D POSITIVE or NEGATIVE? (1)
7.6 Calculate the magnitude of the charge on sphere D. (3)
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