Simulation · Physics · Class 12
Field lines of two charges
From the lesson Electric field lines in Electric Charges and Fields. Change the values and watch what happens.
Field lines of two chargesPhysics · Class 12
The idea behind it
NCERT §1.8
- A field line is a curve whose tangent at every point gives the direction of the net field there; an arrow on it shows which way. Field lines are curves in three dimensions.
- The relative closeness of lines shows the relative strength of the field: lines crowd where E is strong and spread out where it is weak. In a uniform field they are equally spaced parallel straight lines.
- For a point charge the number of lines through a sphere around it is the same at every radius, while the area grows as r², which is the picture behind E ∝ 1/r². (Solid angle ΔΩ = ΔS/r².)
- Lines begin on + charges and finish on − charges; around a lone charge they run out to, or in from, infinity.
- In a charge-free region field lines are continuous curves with no breaks.
- Two field lines never cross, because at the crossing point the field would have two directions.
- Electrostatic field lines never form closed loops, because the electrostatic field is conservative.
- Faraday invented the picture and called them lines of force; the number drawn is a choice, only their relative density means anything.