Question

2 identical balls,each of mass 0.1×10^-3 kg, carry identical charges and are suspended by two threads of equal length. At equilibrium they position themselves as shown in figure. Calculate the charge on either ball.
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Answer 1

Since the two balls have identical charges. So they will repel each other by a force qE. There is another force acting downward is mg.

The force 'mg' and 'qE' are perpendicular to each other.

So, (qE/mg)= tanθ

=> qE= mg.tanθ

=> kq²/r²= mg.tanθ

=> q²= r².mg.tanθ/ k

=>q= √(r².mg.tanθ/ k)

Given r= 0.4 m

=> q= √[{0.4²×0.1×10⁻³×(1/√3)}/k]

       = 0.1 ×10⁻⁶C

       = 0.1 μC

   

Answer 2

Answer:

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