# Why do the electric field directions of opposite charges align in the middle?

• phy77
In summary, when finding the electric field strength between two charges, the direction of the force on the negative charge is in the same direction as the positive charge, rather than opposite as would be expected for unlike charges. This is because the electric field originates from the positive charge and flows towards the negative charge. This can be visualized by imagining a positive test charge placed between the two charges, which would experience a force directed towards the positive charge. This may seem counterintuitive, but can be better understood by visualizing the charges in a circular motion around the test charge.
phy77
but let say you have two charges + and - and they are 30 cm apart, why is it that when your finding the electric field strength in the midde the charges that the direction of the force of the - charge is in the SAME direction as the + charge.. Shouldnt it be opposite and unlike charges attract??

The electric field originates from the +ve charge and flows to the -ve charge.

The force on the -ve charge BY the +ve charge is directed towards the +ve charge.
The force on the +ve charge BY the -ve charge is directed towards the -ve charge.

A positive test charge between the two will experience a force described by the electric field lines--i.e. in the direction of the vector from the +ve charge to the -ve charge.

I'm not sure what you were saying, but hopefully this clears some of it up.

phy77 said:
Shouldnt it be opposite and unlike charges attract??

If the two charges were side-by-side, then the field directions would be opposite.

Now move one of the charges in a circle round to the other side of the test charge - can you see that its field direction will go round with it, so that the two field directions are now the same?

## What is the direction of the electric field?

The direction of the electric field is the direction that a positive test charge would move when placed in the field. This direction is determined by the direction of the force on the test charge, which is always in the direction of the electric field lines.

## How is the direction of the electric field represented?

The direction of the electric field is represented by electric field lines. These lines are drawn in the direction that a positive test charge would move when placed in the field. The lines are closer together where the field is stronger and farther apart where the field is weaker.

## What is the difference between the direction of the electric field and the direction of the electric current?

The direction of the electric field is the direction that a positive test charge would move when placed in the field, while the direction of the electric current is the direction that positive charges would actually flow. In most cases, the direction of the electric field and the direction of the electric current are the same, but there are some cases where they can be different, such as in a capacitor.

## How is the direction of the electric field affected by the presence of a charged object?

The presence of a charged object can alter the direction of the electric field. If the charged object is positive, it will create an electric field that points away from it. If the charged object is negative, it will create an electric field that points towards it. The strength of the electric field will also be affected by the magnitude of the charge on the object.

## Can the direction of the electric field be changed?

Yes, the direction of the electric field can be changed by altering the position or charge of the objects creating the field. The direction of the electric field can also be changed by the presence of other charged objects in the vicinity. In some cases, external forces such as magnetic fields can also change the direction of the electric field.

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