question_answer

Two spherical conductors A and B of radius a and b (b > a) are placed in air concentrically B is given charge + Q coulomb and A is grounded. The equivalent capacitance of these is                                            [MP PMT 2001]

A)            \[4\pi {{\varepsilon }_{0}}\frac{ab}{b-a}\]                  

B)            \[4\pi {{\varepsilon }_{0}}\,(a+b)\]

C)            \[4\pi {{\varepsilon }_{0}}b\]

D)            \[4\pi {{\varepsilon }_{0}}\frac{{{b}^{2}}}{b-a}\]