Two objects each carry positive charge and are brought near. What happens?
Gravity's arrows all point one way: inward. Electric field drawings cannot copy that, because a charged object can be attracted or repelled, depending on the two charges. So which way should the arrows point?
The mapmakers settled it with a convention: every electric field is probed with the same kind of test object.
Here is the field around a positively charged sphere. Like charges repel, so the force on the positive test charge acts away from the sphere. The lines point away from positive charge.
Now the field around a negatively charged sphere. Unlike charges attract, so the force on the positive test charge acts toward the sphere. The lines point toward negative charge.
One convention, two directions. Here they are as a table: each field source, and where its lines point.
The probe is always positive. That single agreement lets every physicist read every electric field drawing the same way.
Field lines around a charged marble point outward, away from it. What is the sign of its charge?
A sphere carries negative charge. Which way do its electric field lines point?
Electric field lines show the force direction on which kind of test charge?
Which pairing of charge sign and line direction is correct?
A balloon rubbed on a sweater carries negative charge. Which way do the field lines around the balloon point?
At point P near a charged rod, the field pushes a positive test charge to the left. Which way does the electric field line at P point?