Quizbank/Electricity and Magnetism (calculus based)/QBCh5

QB153086031104

QB:Ch 5:V1
QB153086031104 1) Three small charged objects are placed as shown, where $$b=2a$$, and $$a=2\times 10^{-7}\text{m}$$.what angle does the force on $$q_2$$ make above the $$-x$$ axis if $$q_1=2e$$, $$q_2=-7e$$, and $$q_3=5e$$?
 * a) 4.357E+01 degrees
 * b) 4.793E+01 degrees
 * c) 5.272E+01 degrees
 * d) 5.799E+01 degrees
 * e) 6.379E+01 degrees

2) A ring is uniformly charged with a net charge of 7 nC. The radius of the ring is R=1.7 m, with its center at the origin and oriented normal to the z axis as shown. What is the magnitude of the electric field at a distance z=1.2 m (on axis) away from the loop's center?
 * a) 6.925E+09 N/C2
 * b) 7.617E+09 N/C2
 * c) 8.379E+09 N/C2
 * d) 9.217E+09 N/C2
 * e) 1.014E+10 N/C2

3) $$E(z)=\int_{0}^R f(r',z)dr'$$ is an integral that calculates the magnitude of the electric field at a distance $$z$$ fromthe center of a thin circular disk as measured along a line normal to the plane of the disk.  The disk's radius is $$R=8.1\text{ m}$$ and the surface charge density is $$\sigma=3\text{ nC/m}^3$$. Evaluate $$f(r',z)$$ at $$r'=4.2\text{ m}$$.
 * a) 5.134E-01 V/m2
 * b) 5.648E-01 V/m2
 * c) 6.212E-01 V/m2
 * d) 6.834E-01 V/m2
 * e) 7.517E-01 V/m2