In silicon, the conduction and valence brands lie close in energy, so that when light is absorbed, electrons can be excited from the valence to the conduction band where they can travel freely through the solid.
a. why does pure silicon not produce a measurable current?
b. describe the effect of doping silicon with indium. what type of semiconductor is produced?
c. in building a photovoltaic cell, it does not matter which semiconducting layer (p or n) is on top (i. e. first contact with sunlight). however, it is important that the top layer be thin. why?

Answer asap need to be answered by wednesday morning explain how a buffer works, using an ethanoic acid / sodium ethanoate system including how the system resists changes in ph upon addition of a small amount of base and upon addition of a small amount of acid respectively. include the following calculations in your i. calculate the ph of a solution made by mixing 25cm3 0.1m ch3cooh and 40cm3 0.1m ch3coo-na+. [ka = 1.74 x 10-5 m] ii. calculate the ph following the addition of a 10cm3 portion of 0.08 m naoh to 500cm3 of this buffer solution. iii. calculate the ph following the addition of a 10cm3 portion of 0.08 m hcl to 200cm3 of the original buffer solution.