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Decibel Measurements
19 questions By Tony R. Kuphaldt
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Question 10 of 19
What does it mean to speak of the gain of a circuit? This term is very commonly used when describing amplifier circuits, but it may also be used to describe circuits containing nothing but passive components, and are thus incapable of amplifying.
What letter is used to symbolize gain in mathematical equations?
Reveal answer“Gain” (A) refers to the ratio of output signal compared to input signal.
Notes:Discuss what it means for a circuit to have a designated “output” and “input”. Can they think of any circuits studied thus far that have places to input and output signals?
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Question 11 of 19
Calculate the voltage gain of this circuit, if R1 has a resistance of 8.1 kΩ and R2 has a resistance of 1.75 kΩ:
Reveal answerAV = 0.178
Follow-up question: how does this gain figure (AV) relate to the “voltage divider formula”?
ER = Etotal ( R Rtotal) Notes:Students should readily recognize this circuit as a voltage divider, from their education in basic DC circuits. Though it may seem strange to calculate the “gain” of a completely passive and indeed dissipative circuit, it is entirely valid.
Discuss with your students the maximum and minimum possible power gain values for a circuit of this type.
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Question 12 of 19
Calculate the power gain of this circuit, if R1 has a resistance of 1 kΩ, R2 has a resistance of 5.1 kΩ, and the load has a resistance of 10 kΩ:
Reveal answerAP = 0.261
Follow-up question: what unit does this figure have, if any?
Notes:Students should readily recognize this circuit from their education in basic DC circuits. Though it may seem strange to calculate the “gain” of a completely passive and indeed dissipative circuit, it is entirely valid.
Discuss with your students the maximum and minimum possible power gain values for a circuit of this type. Also discuss with them the nature of ratios with regard to units.
