A slab of plate glass containing dissolved helium is placed in a vacuum furnace at a temperature of 400 C to remove the helium from the glass. The concentration of helium is constant throughout the glass before vacuum heat treatment. After 10 minutes in vacuum at 400 C, at what depth from the surface of the glass has the concentration of helium decreased to 1/3 of its initial value? Express your answer in meters. The diffusion coefficient of helium in plate glass at 400 C is 3.091 x 10-6 cm2/s
1 answer
0.000258