Read the following passage and then answer questions on the basis of your under standing of the passage and the related studied concepts. Passage : For many purposes it is necessary to change an alternating voltage from one value to another value of greater/smaller magnitude. This is done with a device called transformer. A transformer consists of two sets of coils of enamelled copper wire, insulated from each other, wound on a laminated soft iron core. The primary coil has N_(p)turns and an alternating input voltage V_(p)is applied to the primary coil. The secondary coil has N_(s)turns and produced an output voltage V_(s)when circuit of the secondary coil is an open circuit. For an ideal transformer, in which the primary has negligible resistance and all the flux in the core links both primary and secondary windings. For such a transformer V_(s)/V_(p) = N_(s)/N_(p) =k (a)Distinguish between a step up transformer and a step down transformer.