Attix 12.1 A conventional standard free-air chamber has a diaphragm aperture 1.30 cm in diameter and a collector plate 12.0 cm long, separated by guard plates by 0.5 mm gaps. The distance from the diaphragm to the front edge of the collector plate is 30 cm. The dry air in the chamber is at 23.1 C, 755 torr and (u/p)air 0.155 cm2/g, fe 0.001 and fa = 0.004. Calculate the exposure at the diaphragm for a charge Q 6.17x10 C (corrected for ion recombination). Give the answer in C/kg and roentgens.