JEE Mains · Physics · STD 12 - 1. Electric charges and fields
The volume charge density of a sphere of radius \(6 \,m\) is \(2 \,\mu cm ^{-3}\). The number of lines of force per unit surface area coming out from the surface of the sphere is \(....\times 10^{10}\, NC ^{-1}\). [Given : Permittivity of vacuum \(\left.\epsilon_{0}=8.85 \times 10^{-12} C ^{2} N ^{-1}- m ^{-2}\right]\)
- A \(44\)
- B \(43\)
- C \(45\)
- D \(42\)
Answer & Solution
Correct Answer
(C) \(45\)
Step-by-step Solution
Detailed explanation
No. of electric field lines per unit area \(=\) electric field. \(E =\frac{\rho r}{3 \epsilon_{0}}, \text { for } r=R\) \(E=\frac{\rho R}{3 \epsilon_{0}}=\frac{2 \times 6}{3 \times 8.85 \times 10^{-12}}=0.45 \times 10^{12}\,NC ^{-1}\) \(=45 \times 10^{10}\,N / C\)
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