Two charges, -15 and +3.6 Solution Take the positive charge at position x = 0; w

Question

Two charges, -15 and +3.6

Explanation / Answer

Take the positive charge at position x = 0; with the negative charge at x = 3.0. For locations of x > 3, the field from the + charge is + (in the direction of +x), while the field from the negative charge is - (in the direction of -x). You can expect that at some point the fields could cancel in the region x > 3.0. Between the charges, the field from both is positive (in the +x direction), and there can be no null point there. For x < 0, the field from the + charge is negative, while the field from the - charge is positive (in the +x direction). Cancellation can occur in that region also. Conditions for cancellation when x > 3: K*15/(x - 3.6)² = K*2.9/x² 16*x² = 4*(x - 3.0)² Conditions for cancellation when x < 0 K*4/x² = K*16/(x + 3.0)² 4*(x + 3.0)² = 16*x² Multiply these out and solve the quadratics for x. You may get two real values, which means cancellation may exist for both regions. EDIT: Note that you will get the same answer from either of these equations, since the values you get from the second are for -x. If the field at a point is 0, it doesn't matter what charge you place there, the force will be 0.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

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