A small sphere with mass `1.2 g` hangs by a thread between two parallel vertical plates `5.00 cm` apart. The plates are insulating and have uniform surface charge densities `+ sigma and - sigma`. The charge on the sphere is `q = 9 xx 10^-6 C`. What potential difference between the plates will cause the thread to assume an angle of `37^(@)` with the vertical as shown in (Fig. 3.134) ? .A. 30 VB. 12 VC. 50 VD. 25 V

A small sphere with mass `1.2 g` hangs by a thread between two paralle

1.	A small sphere with mass `1.2 g` hangs by a thread between two parallel vertical plates `5.00 cm` apart. The plates are insulating and have uniform surface charge densities `+ sigma and - sigma`. The charge on the sphere is `q = 9 xx 10^-6 C`. What potential difference between the plates will cause the thread to assume an angle of `37^(@)` with the vertical as shown in (Fig. 3.134) ? .A. 30 VB. 12 VC. 50 VD. 25 V
Answer» Correct Answer - c `F_e = m g tan theta` =`(1.20 xx 10^-3 kg)(10 ms^-2) tan (37^(@)) = 0.0090 N` `F_e = E q = (V q)/D` `:. V = (F_e d)/q = ((0.009 N)(0.0500 m))/(9.0 xx 10^-6 C) = 50.0 V`.

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