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Question

A test charge of +9 x 10-6 C experiences a downward electrostatic force of 15 N when placed at a certain point in space. What are the magnitude and direction of the electric field at this point?

Answer 1

Ok, for this problem, let's remeber the second law of Newton :

E*q = Force

where :

E = electric field

q = charge

E*9*10^-6 = 15

E = 1.6*10^6 (N/C)

This is the magnitude of the electric field

now the problem says that the charge experiences a downward electrostatic force, so it will be -j

Direction of the force : -j

Now : E*q = force

the direction of the electric field will be equal to the direction of the force that is "-j" downward

so direction of "E" = -j
q = charge