A piezoelectric force transducer has a charge sensitivity of 20 pC/N. It is connected to a charge amplifier and overall gain of transducer and amplifier is 50 mV/N. The gain of the amplifier is :
MH SET - 2018, SET Exam - 2018,
Answer: C
The amplifier gain is 2.5 mV/pC.
The overall sensitivity is the product of the transducer's sensitivity and the amplifier's gain, so the amplifier gain is the overall gain divided by the transducer's:
\[ \begin{aligned} G &= \frac{50\ \text{mV/N}}{20\ \text{pC/N}} \\ &= 2.5\ \text{mV/pC} \end{aligned} \]
The newtons cancel, leaving millivolts per picocoulomb, the natural unit for a charge amplifier. 1 mV/pC and 1.5 mV/pC would give an overall gain of only 20 or 30 mV/N, and 4 mV/pC would give 80 mV/N.
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