Question-

Pocket ionization chambers are built in the form of an electrical capacitor. You know that capacitance is equal to a change in charge over a change in voltage, as C, where the capacitance, C, is in Farads (F), the voltage, V, is in volts (V) and the charge, Q, is in coulombs (C).

You have a chamber that has a sensitive cylindrical volume radius of 0.635 cm and length 6.35 cm. The standard density of the air in the chamber is 0.001293 g/cm^3. The chamber is calibrated such that its quartz fibre has full deflection when there is 50 uC per kg of air. The capacitance of the chamber is 10 pF.

a) If it takes 200 Volts to charge the chamber, what is the voltage in the chamber at full scale deflection?

b) What exposure (in Roentgen) does full scale deflection correspond to? What absorbed dose in air, and tissue, does it correspond to?