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Two point charges +4q and +q are placed 30 cm apart. At what point on the line joining them the electric field is zero?
- A 20 cm from the charge 4q
- B 15 cm from the charge q
- C 7.5 cm from the charge q
- D 5 cm from the charge q
That's Correct!
It's Wrong!
The electric field at a point on the line joining two charges is zero when the magnitudes of the electric fields produced by the charges at that point are equal and opposite. In this case, the charge +4q produces an electric field that is four times stronger than the electric field produced by the charge +q. To balance out the stronger electric field, the point where the electric field is zero must be closer to the charge +4q. Therefore, the correct answer is 20 cm from the charge 4q.
