Question

Two balls A and B of same mass (M) and charges Q,-Qare suspended by two strings of same length from two different suspension points S1 and S2. If S1S2 = 3x and AB = x then show that :
a) tension in string is T = Q²L/4πε₀x³

Answer 1

EXPLANATION.

Tcos ø = Mg ......(1)

Tsin ø = F ........(2)

=> F = kq² / r = Q² / 4π€o

From equation (1) and (2)

we get,

=> Tan ø = Q² / 4π€•mgx²

From equation (2)

we get,

=> T = F / sin ø

=> T = Q² / 4π€•x² sin ø

=> 2L sin ø = 2x

=> L sin ø = x

=> sin ø = x/L

put the value of sin ø in equation

we get,

=> T = Q²L / 4π€•x³

Note = Also see the image

attachment.