up 1 cm on 51 cm string
cos A = 50/51
sin A = side force F/ Tension T
tan A = F/(mg)
so
F/mg = tan 11.36 = .201
F = .001 (9.81)(.201) = .00197 Newtons
F = Q E
.00197 = Q * 9200
Q = 2.14 * 10^-7 Coulomb
If motion in direction of E field, charge positive
A point charge (m = 1.0 g) at the end of an insulating string of length L = 51 cm (Fig. 16-66) is observed to be in equilibrium in a uniform horizontal electric field of E = 9200 N/C, when the pendulum's position is as shown in Fig. 16-66, with the charge d = 1.0 cm above the lowest (vertical) position. If the field points to the right in Fig. 16-66, determine the magnitude and sign of the point charge.
1 answer
0 answers