Capacitance — UPSC Physics Optional CSE 2002 Paper I

A Geiger tube consists of a wire a wire of radius 0.2\text{ mm} and length 12\text{ cm} and a co-axial metallic cylinder of radius 1.5\text{ cm} and length 12\text{ cm}. Find

(i) the capacitance of the system, and

(ii) the charge per unit length of the wire when the potential difference between the wire and the cylinder is 1.2\text{ kV}. (Assume the dielectric constant of the gas in the tube to be 1)