Electrostatics 1 Question 20

21. Two small balls having equal positive charges Q (coulomb) on each are suspended by two insulating strings of equal length L (metre) from a hook fixed to a stand. The whole setup is taken in a satellite into space where there is no gravity (state of weightlessness). The angle between the strings is …… and the tension in each string is ………. newton.

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Answer:

Correct Answer: 21. 180\degree,Q216πε0L2

Solution:

  1. Due to electrostatic repulsion the charges will move as farthest as possible and the angle between the two strings will be 180 as shown in figure. Tension in each string will be equal to the electrostatic repulsion between the two charges. Thus,

T=Fe=14πε0Q×Q(2L)2=Q216πε0L2



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