8.5 An alpha particle (charge 3.20×10í^19 C, mass 6.68×10í^27 kg) is in a uniform electric field of strength 7.75×10í^3 N/C. What is
the particle's speed after 12.5 ms?
m/s8.6 A proton with mass 1.67×10í^27 kg and charge 1.60×10í^19 C is traveling at 6.00×10^5 m/s in the positive direction when it
enters a uniform electric field with a strength of 1250 N/C in the negative direction. The opposing electric force brings the
proton to rest. Calculate the displacement of the proton while it is coming to rest.m8.7 A proton with mass 1.67×10í^27 kg and charge 1.60×10í^19 C accelerates from rest in a uniform electric field of strength
500 N/C. (a) What is the magnitude of the acceleration of the proton? (b) How long does it take the proton to reach a speed of
35,000 m/s? (c) What distance has the proton traveled when it reaches this speed? (d) What is the kinetic energy of the
proton at 35,000 m/s?
(a) m/s^2
(b) s
(c) m
(d) JSection 12 - Electric dipoles
12.1 Two opposite point charges of magnitude 2.30eí6 C are located near the origin. The positive charge is at (1.50, 1.50) mm
and the negative charge is at (í1.50, í1.50) mm. What is the magnitude of the dipole moment vector for this pair of charges?
C·m12.2 The magnitude of the dipole moment of a water molecule in liquid water is 6.2×10í^30 C·m. A simplified model of the water
molecule H 2 O can be constructed by imagining that each of the two hydrogen atoms in the molecule contributes its single
electron to the one oxygen atom, and thereby becomes bound to it. In this model, the molecule is a simple dipole, with the
oxygen atom at one end and the two hydrogen atoms at the other, each end having a charge of magnitude 2e = 3.2×10í^19 C.
In this model, what is the dipole separation of the charges in the water molecule?
m
12.3 An electric dipole with moment p = (3.43, í5.63) μC·m consists of two opposite charges of magnitude 1.00x10í^6 C. How far
apart are the charges?
m