Question

One end of a 10cm long silk thread is fixed to a large vertical surface of a charged nonconducting plate having a mass 10g and a charge of 4*10^-6 c . In equlibrium the thread makes an angle of 60 deg. With he vertical.find the surface charge density on plate.
Joshi sir comment

according to the diagram 

tanθ = qE/mg = q(σ/2ε0)/mg

solve this eq. for σ.

Remember that length of the thread is not applicable in the question.

Read 1 Solution.

ANS     7.514*10-7 C/m2

According to the given data in the problem

tanθ= qe/mg

        =q(δ/2ε0)/mg

after substituting the values we get the answer as give above.

BRAHMAIAH 10 year ago is this solution helpfull: 8 4

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