 Previously we looked at the electric field surrounding one particle. Now let's look at the electric field around two particles. Let's say we have one positive particle and one negative particle next to each other. Electric field lines describe the force that a positive particle will experience. To determine the direction of the field lines, we will analyze the direction of the force a positive particle will experience. Let's say we had a positive particle here. Then it would be pushed away from the positive charge and pulled towards the negative charge. So the particle would experience a force to the right and thus the electric field would also point to the right. Let's say you had a positive particle here. Then it would be pushed away from the positive charge and pulled towards the negative charge. However, this particle is closer to the positive charge than the negative charge. And so the force it experiences from the positive charge is bigger than the force it experiences from the negative charge. So overall the particle experiences are forced in this direction. Now doing this again for every single point around these two charges. If we look at the force that the particle experiences at every single point, we can see the electric field. Using field lines to represent the electric field, we would see this picture. The electric field surrounding two oppositely charged particles looks like the magnetic field surrounding a bar magnet. Another way to think of this is with vectors. Let's look at two oppositely charged particles like before. If there is a positive particle here, then there is a force pushing it away from the positive charge and a force pulling it towards the negative charge. Using vector addition, we get the total force this positive particle will experience. This is the vector field representation of the electric field around a positive particle. And the electric field around a negative particle looks like this. If we add up the vectors at a point, we get the total force a positive particle experiences at that point. Now we do this for all points around the charges and we get the electric field lines surrounding the charges. The vector field representation of electric fields can be confusing to look at and understand at a glance. This is why we also use a field line representation. The field lines are actually constructed from vector addition of the electric fields of individual interacting particles. Again, looking at the force a positive particle will experience except this time we have two negative charges. At the middle, a positive particle will be attracted to both negative charges equally and so there is no net force on it at this location. But since electrostatic attraction increases as distance decreases, moving slightly to the left, then the positive particle would experience a force to the left. Moving up slightly will still cause the positive particle to be attracted equally to both negative charges. However, there will be a pull downwards as the attraction to both negative charges don't cancel out. Analyzing some other points, we get the electric field with the vector representation. And this is the field line representation. Analyzing it in terms of vector addition, we have a force to the left from the left negative charge and a force to the right from the right negative charge. Adding the vectors, we get a force pointing down. Thus, a positive particle at this location will experience a force pushing it downwards. So there is an electric field pointing downwards at this location. We can do the same analysis for the other points. Hence the final electric field of these two negative charges will look like this. The vector representation and the field line representation. No matter how you analyze the situation, you'll still get the same result.