Two concentric spherical shells have radii 0.15 m and 0.3 m. The inner sphere is given a charge $-6\times {10}^{-2}\mu C$ . An electron escapes from the inner sphere with negligible speed. Assuming that the region between the spheres is vacuum, the speed with which it will strike the outer sphere is $*\times {10}^{6}m{s}^{-1}$, where * is not readable. Find the value of *. $(\frac{e}{m}forelectron=1.76\times {10}^{11}Ck{g}^{-1})$