Two point charges, q1= + 6.0 nC and q2= + 8.0 nC, are situated as shown below What is the magnitude of the electric force on q2

A positive charge of 4 µC exerts a force of 8 N on an unknown charge 20 cm away. The unknown charge is: Select one: Oa. +44 µC b. None of these O C. +8.9 µC d. -8.9 µC

What is the resultant magnitude and direction of the force on a 5.9 µC charge situated on the y-axis, 5.3 cm from the point of origin, due to a pair of 4.3 µC charges located on the x-axis at opposite sides of the point of origin, each at distance of 4.4 cm from the point of origin? a. 17.2 N b. 74.0 N c. 73.0 N d. 76.0 N e. 61.4 N The surfaces of a lipid bi-layer forming the membrane around a cell with a radius of 1.8 µm has a residual charge qr = 10.6x10-15 C on outside of the bi-layer, and the same amount of negative charge on the inside. What is the force in pN (x10-12 N) on a singly-charged positive ion (q =1.6 ×10-1⁹ C) located on the outer surface of this membrane? Hint: Use F = q E = q (o/e) with o = qr/A = qr/ (4π r²) and = 8.85 x 10-12 F.m-1. Answer:

Four point charges are placed at the corners of a square as shown in the figure. Each side of the square has length 1.0 m. Determine the magnitude of the electric field at the point P, the center of the square. (note Q = 0.15 C) a. no answer is correct b.  5.0 x 10 4 N/C c. 3.6 x 10 4 N/C d. 3.6 x 10 9 N/C e. 5.4 x 10 9 N/C