Electr. and Magnetism
posted by Allan on .
1) A charge of 80nC is uniformly distributed along the x-axis from x= 0 to x= 2.0m. Determine the magnitude of the electric field at a point on the x-axis with x=8.0m.
a] 30 N/C
b] 15 N/C
c] 48 N/C
d] 90 N/C
e] 60 N/C
2) 3 point charges, 2 positive and one negative, each having a magnitude of 20uC are placed at the vertices of an equilateral triangle (30 cm on a side). What is the magnitude of the electrostatic force on one of the positive charges?
1. (b) is closest. You need to use Coulomb's law and integrate the effect of charge from x = 0 to 2, and include the factor epsilono
2. When you use Coulomb's Law to add the vector electrostatic forces, the resultant will be parallel to the opposite side of the triangle.
F = 2 *20uC* epsilon0*sin 30/(0.3)^2
= (20 uC)^2*epsilono /0.09 m^2
= 40 N