14. An LED is constructed from a p-n junction based on a certain Ga-As-P semiconducting material whose energy gap is Eg. What is the wavelength of the emitted light?Ans：___(18)____

(a).Suppose that the cylinder is sliding without rolling down the smooth inclined face of the wedge, and the wedge is free to move on a horizontal plane with friction. How far has the wedge moved by the time the cylinder has descended from a rest a vertical distance h?Ans：___(1)____