Question
19. Two point charges of values +3.4 and +6.6 IC, respectively, are separated by 0.20 m. What is the potential energy of this 2-charge system? (-8.99 × 10" N-mC) a. +0.34 J b.-0.75 J c. +1.0J d.-3.4) 20. Two point charges of values +3.4 and-6.6 C are separated by 0.10 m. What is the electrical potential at the point midway between the two point charges? (k, 8.99x 10 N m/C) a.+1.8 x 10" b.-0.90 x 10V c, +0.90 × 10° v d. +3.6× 106 V 21. A point charge of +3.0 C is located at the origin of a coordinate system and a second point charge of -6.0 jC is atx 1.0 m. At what point on the x axis is the electrical potential zero a-0.25 m b. +0.25 m c. +0.33 m d. +0.75 m 22. Two protons, each of charge 1.60 x 10" C, are 2.00 x 10- m apart. What is the change in potential energy if they are brought 1.00 x 10 m closer together? (k 8.99x 10 N /C) a. 1.15 x 10-23J b. 3.20 x 10-J c. 3.20 x 10-16J d. 1.60× 10-14 J 23. If a doubly-ionized oxygen atom (0) is accelerated from rest by going through a potential difference of 20 V, what will be the change in its kinetic energy? a. 10 eV b. 20 eV c. 40 eV d. none of the above
Explanation / Answer
19) Potential energy = kq1q2 / r
= 9*10^9*3.4*10^-6*6.6*10^-6/ 0.2
= 1.0098 J
so option c) is correct
20) electric potential = kq1/r1 + kq2 / r2
= 9*10^9*10^-6*(3.4 / 0.05 + 6.6 / 0.05)
= 1.8*10^6 V
so option a) is the correct answer