Physics/Charges

posted by .

Point charges Q1 = 50 µC and Q2 = -20 µC are placed 2 meters apart. Where can I put a third charge so that the net electrical force on it is zero?

• Physics/Charges -

I'm a little rusty on this, but I think you need the charge of the one that you are putting in the middle. Was that provided to you?

• Physics/Charges -

I apologize, you do not have to know it, it is not needed.

Let the distance between Q1 and Qo equal x(r1), and the distance between Q2 and Qo equal x-2m (r2).

Using the sum of forces,

F1onO=F2onO

Ko[(Q1Qo)]/r^2=Ko[(Q1Qo)/r^2]

Ko and Qo cancel each other out leaving

Q1/r^2=Q2/r^2

Plugging in my values for Q1 and r, and r2

(50 x10^-6 C/x^2)=( -20 x10^-6 C)/(2-x)^2

Since they are both in µ C, rewrite the equation as

(50/x^2)=( -20)/(2-x)^2)

50(2-x)^2=-20(x^2)

50(x^2-4x+4)=-20x^2
50x^2-200x+200=-20x^2

factoring out 10,
5x^2-20x+20=-2x^2

7x^20x+20=0

Use the quadratic equation to solve for x

I hope this helps, but I am not that positive.

• Physics/Charges -

Last set of values should read:

7x^2-20x+20=0

Similar Questions

1. physics

Two point charges, q1 and q2, are placed 0.30 m apart on the x-axis, as shown in the figure above. Charge q1 has a value of –3.0 x 10–9 C. The net electric field at point P is zero Q: Calculate the magnitude of charge q2. Q: Calculate …
2. physics

Two spheres with charges of 4.00nC and 3.00nC are placed 0.500m apart. At what point between the two charges must the third charge of 2.00cN be placed so that the net electrostatic force acting on this charge is zero?
3. physics

Consider a charge of +2.0 C placed at the origin of an X-Y co-ordinate system and a charge of -4.0 C placed 40.0 cm to the right. Where must a third charge be placed – between the charges, to the left of the origin, …
4. SIMPLE pHYsics....

Two positive point charges are placed on the x-axis. One, of magnitude 4Q, is placed at the origin. The other, of magnitude Q is placed at x=3 m. Neither charge is able to move. Where on the x-axis in meters can I place a third positive …
5. Physics

Two positive point charges are placed on the x-axis. One, of magnitude 4Q, is placed at the origin. The other, of magnitude Q is placed at x=3 m. Neither charge is able to move. Where on the x-axis in meters can I place a third positive …
6. Physics (Electricity & Magnetism))

Two positive point charges are placed on the x-axis. One, of magnitude 4Q, is placed at the origin. The other, of magnitude Q is placed at x=3 m. Neither charge is able to move. Where on the x-axis in meters can I place a third positive …
7. Physics

Two positive point charges are placed on the x-axis. One, of magnitude 4Q, is placed at the origin. The other, of magnitude Q is placed at x=3 m. Neither charge is able to move. Where on the x-axis in meters can I place a third positive …
8. Physics

Consider two charges Q and q separated by a distance d . If the potential at the point p (which is in right side from both charges) is V=0 , we can conclude (one answer only): a)no net force would act on a test charge located at P …
9. Physics

Consider two charges Q and q separated by a distance d . If the potential at the point p (which is in right side from both charges) is V=0 , we can conclude (one answer only): a)no net force would act on a test charge located at P …