4. Charge q1 = +5.4 Mu C and charge q2 = -3.8 Mu C lie on the x-axis, as shown.

Question

4. Charge q1 = +5.4 Mu C and charge q2 = -3.8 Mu C lie on the x-axis, as shown. Charge q1 is at the origin and charge q2 is at the location x2 = 1.32 m. a. Calculate a location (not infinitely far away) where the electric potential is zero. b. Calculate a location (not infinitely far away) where the magnitude of the electric field is zero. c. A charge q3 + 6.7 Mu C is brought from infinitely far away to the location you calculated in part a. How much work is required to do this? d. The same charge q3 = +6.7 Mu C is brought from infinitely far away to the location in part b. How much work is required to do this?

Explanation / Answer

a)
let at x=x, Vnet = 0

V1 = V2

k*q1/x = k*q2/(1.32-x)

q1/x = q2/(1.32-x)

5.4/x = 3.8/(1.32-x)

5.4*1.32 - 5.4*x = 3.8*x

x = 5.4*1.32/(5.4+3.8)

= 0.775 m <<<<<<<<<<<<<<<<<<<----------Answer

b) let at x=x, Enet = 0

E1 = E2

k*q1/x^2 = k*q2/(x-1.32)^2

(x-1.32)^2/x^2 = q2/q1

(x-1.32)/x = sqrt(q2/q1)

(x-1.32)/x = sqrt(3.8/5.4)

(x-1.32)/x = 0.839

x - 1.32 = 0.839*x

x(1-0.839) = 1.32

x = 1.32/(1-0.839)

= 8.2 m <<<<<<<<<<<<<<<<<<<----------Answer

c) Workdone = q*delta_V

= q*0

= 0 <<<<<<<<<<<<<<<<<<<----------Answer

d) U1 = 0

U2 = k*q1*q3/x + k*q2*q3/(x-1.32)

= 9*10^9*5.4*10^-6*6.7*10^-6/8.2 - 9*10^9*3.8*10^-6*6.7*10^-6/(8.2-1.32)

= 6.4*10^-3 J

Workdone = U2 - U1

= 6.4*10^-3 J <<<<<<<<<<<<<<<<<<<----------Answer

Related Questions

Navigate

• Browse (All)
• Browse 4
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.