Point charges in plane

Electricity and Magnetism Level 2

As shown above, two point charges $A$ and $B$ are fixed on the $x$ -axis with an equal distance of $d$ from the origin $O.$ $A$ is charged negatively, while $B$ is charged positively. The quantities of the electric charges on $A$ and $B$ are the same. The distances between the origin $O$ and the two points $P$ and $Q$ on the $y$ -axis are also the same, which is $d.$ Which of the following is correct?

a) The electric field intensities at $P$ and $Q$ are the same.

b) The direction of the electric field at $O$ is the $-x$ direction.

c) If we move the point charge $A$ to $O$ , then the directions of the electric fields at $P$ and $Q$ are the same.

a), b) and c) a) only c) only a) and b)

1 solution

Alakh Aggarwal
May 14, 2014

It is a dipole with P and Q at equator......... thus a is true... with magnitude of electric field - kp/r^3 ..........r is same for P and Q...... b is true.... electric field goes from positive charge to negative charge....... 3rd remains false..... as when -ve charge is brought at O...... electric field due to -ve charge at P will only be along Y axis..... but due to +ve charge will be along both X and Y axis.... thus net Electric field is somewhat at an angle with X axis.... so.... there direction is not same at P and Q.........

Point charges in plane

1 solution

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