Use of dB in a multistage voltage amplifier. When high amplification is required, it is not usually possible to do so with a single amplification stage, for a number of reasons. For example, a simple transistor amplifier is typically limited to an amplification of about 100 or less. More complex amplifiers, such as the operational amplifier, are also limited to reasonably low amplification because of bandwidth requirements. Therefore, multistage amplifiers are a necessity whereby the output of one stage is fed as the input to the next stage. Suppose a high-frequency amplifier is required with an amplification (often called gain) of 120 dB. Assuming that individual amplifiers with amplification between 1 and 50 are available, what is the minimum number of amplifiers needed and what are their amplifications

Acommercial grade cubical freezer, 4 m on a side, has a composite wall consisting of an exterior sheet of 5.0-mm thick plain carbon steel (kst= 60.5 w/m k), an intermediate layer of 100-mm thick polyurethane insulation (kins 0.02 w/m k), and an inner sheet of 5.0- mm thick aluminium alloy (kal polyurethane insulation and both metallic sheets are each characterized by a thermal contact resistance of r 2.5 x 104 m2 k/w. (a) what is the steady-state cooling load that must be maintained by the refrigerator under conditions for which the outer and inner surface temperatures are 25°c and -5°c, respectively? (b) for power saving purpose, which wall material should be increased/reduced in. thickness in order to reduce 50% of the cooling load found in part (a)? redesign the thickness of the proposed material. 177 w/m-k). adhesive interfaces between the q=575.93 w