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Thank youuu soo much!The concept here is pretty straightforward - at any point in an electric field, the force on a charged particle acts along the tangent to the electric field line at that point.
In other words, the force on a particle placed on a curved field line will act along the direction of the tangent of the field line at that point.
Also, the arrows on electric field lines (in diagrams only) tell you the direction of the force a positively charged particle would experience in the field - a negatively charged particle will experience a force along the opposite direction.
So the positive particle faces a force along the arrow, the negatively charged particle experiences a force in the direction opposite the arrow.
View attachment 44886
On the diagram above, the blue arrows represent forces on a negative charge (D,E,F) and the red arrows represent force on a positive charge(A,B,C). You'll note that both the forces at any point act along the tangent to that point, just in opposite directions (NOTE: The arrows here are not drawn to scale, so do not concern yourself with the length of the arrows and the magnitude of the field - here, just focus on the directions relative to the field lines).
The tangent represents the direction of the electric field at that point, so the electric field direction can be said to be in the direction of a force on a positive particle at that point in the field, with the force on a negative particle in the opposite direction.
So, in this question, the electric field arrows points to the right, and the lines are all straight and evenly spaced. Therefore, this is a uniform electric field, with the forces on a proton placed anywhere in this field acting to the right.
Therefore, the force on an electron (as in the question) should be in the opposite direction, i.e. to the left. The correct answer is, therefore, B.
Hope this helped!
Good Luck for all your exams!
