Question

In the figure particle 1 of charge q₁ = 0.93 μC and particle 2 of charge q₂ = -2.96 μC, are held at separation L = 9.5 cm on an x axis. If particle 3 of unknown charge q₃ is to be located such that the net electrostatic force on it from particles 1 and 2 is zero, what must be the (a)x and (b)y coordinates of particle 3?

Answer 1

Let us start the solution, by assuming that the charge   is located at the origin (0,0) and the charge   is located at a distance 9.5 cm to the right of  .

The test charge 'Q' must be situation on x axis to the left of the . The reason behind this is as follows:

As the the strength of   is lower than , the the repulsive force on Q ( directed outward) due to   would be comparable to the attractive force (in order to have Net force to be Zero) on Q ( directed inward) due to  , if the test charge Q situated closer to  .

In order to have net force on Q to be equal to zero, we must have,

Now, if we equate both the force on Q, putting all the numbers, we will get that the test charge Q will be situated x=12.1 cm to the left of   and 21.6 cm to the left of  ​​​​​​.

The x co ordinate of the test charge would be 12.1 cm and y co-ordinate would be zero.