Answer:
[tex]n = 1.266\times 10^{12}[/tex]
Explanation:
Given data:
mass of sphere is 10 g
Angle between string and vertical axis is [tex]\theta = 13 degree[/tex]
thickness of string 300 mm = 0.3 m
[tex]sin\theta =\frac{2}{0.3 m}[/tex]
r =0.3 sin 13 = 0.067 m
[tex]Fe = \frac{ kq_1 q-2}{d^2}[/tex]
[tex]Fe = \frac{kq^2}{(2r)^2} = mg tan\theta[/tex]
[tex]q^2 = mg tan\theta \frac{(2r)^2}{k}[/tex]
[tex] = 0.0091 \times 9.8 tan13 \times \frac{(2\times 0.067)^2}{9\times 10^9}[/tex]
[tex]q^2 = 4.10\times 10^{-14}[/tex]
[tex]q = 2.026 \times 10^{-7} C[/tex]
q = ne
[tex]n = \frac{1.6\times 10^{-19}}{2.02\times 10^{-7}}[/tex]
[tex]n = 1.266\times 10^{12}[/tex]
