A hollow cylinder has a charges q coulomb within it. If `phi ` is the electric flux in units of V-m associated with the curved surface B, the flux linked with the plane surface A in units of V-m will be

Options

A. `(q)/(2in _0) `
B. `(phi)/(3) `
C. ` (q)/( in_0) -phi`
D. ` (1)/(2) [( q)/(in _0) -phi ]`

Answer

D

Explanation

Total flux over entire cylinder `=(q)/(in_0) ` From symmetry `phi_A =phi_C and phi_B= phi `
` therefore " "phi_A+phi_B+phi_C=phi_A+phi +phi__A=phi_A=(q)/(in_0) rArr phi_A=(1)/(2) [(q)/(in_0) -phi]`