48 you are given two amplifiers, a and b, to connect in cascade between a 10-mv, 100-k source and a 100- load. the amplifiers have voltage gain, input resistance, and output resistance as follows: for a, 100 v/v, 100 k,10k, respectively; for b, 10 v/v, 10 k,1 k, respectively. your problem is to decide how the amplifiers should be connected. to proceed, evaluate the two possible connections between source s and load l, namely, sabl and sbal. find the voltage gain for each both as a ratio and in decibels. which amplifier arrangement is best?

SABL

Explanation:

The best amplifier will be the one that gives us a bigger gain. In each stage will be a load factor that will reduce the gain, that is defined as:

where Rin is the input resistance of the next stage and Rout the output resistance of the previous stage.

Analyzing SABL:

the total gain will be the total gain of each stage multiplied by the load factor.

Analyzing SBAL:

the total gain will be the total gain of each stage multiplied by the load factor.

So the best amplifier arrangement is SABL.

96.77 amp

explanation:

rl = 250/100 = 2.5 ohms.

egl = 250 + (100 × 0.1) + 2 = 262 v.

at 700 r.p.m., eg2 = 262 × 700/1000 = 183.4 v.

if ia is the new current, then eg2 - 2 - (ia × 0.1) = 2.5 ia

which means this will give ia = 96.77 amp.