Asample semiconductor has a cross-sectional area of 1 cm and a thickness of 0.2 cm. five watts of electromagnetic radiation at a wavelength of 6200 angstroms are incident on this material. assume that 80% of the photons are successful in generating an electron-hole pair. determine the number of electron-hole pairs generated per unit volume per unit time.

Two conductors, a and b, are each in the shape of a tetrahedron. but of different sizes. they are charged in the following manner: 1. tetrahedron a is charged from an electrostatic generator to charge q. 2. tetrahedron a is briefly touched to tetrahedron b. 3. steps 1 and 2 are repeated until the charge on tetrahedron b reaches a maximum value. if the charge on tetrahedron b was q/4 after the first time it touched tetrahedron a. what is the final charge qbmax on tetrahedron b?