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Select the most appropriate options to fill in the blanks. Piezoelectric transducers exhibit ____ sensitivity to dynamic changes and their output is ____ dependent on the mechanical stress applied.
low, inversely
high, linearly
moderate, exponentially
zero, independent
high, linearly
Piezoelectric transducers convert mechanical stress directly into electrical charge. They are highly responsive to rapid (dynamic) changes in input, making them ideal for vibration and shock measurements, and their output voltage is directly proportional to the applied mechanical force within their linear operating range.
Piezoelectric transducers convert mechanical stress directly into electrical charge. They are highly responsive to rapid (dynamic) changes in input, making them ideal for vibration and shock measurements, and their output voltage is directly proportional to the applied mechanical force within their linear operating range.
Q=dтЛЕF тАФ where Q is charge, d is the piezoelectric charge constant, and F is the applied force.
V=CQтАЛ=CdтЛЕFтАЛ тАФ where V is output voltage and C is the capacitance of the sensor element.
When a mechanical force is applied to a piezoelectric crystal (like quartz or PZT), the internal dipole moments rearrange, causing an accumulation of charges on opposite surfaces of the material. This phenomenon, known as the piezoelectric effect, generates an electric potential difference V across the electrodes. The magnitude of this output is V=AgтЛЕtтЛЕFтАЛ, where the charge is linearly related to the stress.
Piezoelectric sensors are active transducers because they generate their own electrical output.
They are excellent for high-frequency measurements but unsuitable for static (DC) measurements due to charge leakage.
The linear relationship holds as long as the crystal is not subjected to mechanical failure or thermal limit exceeds.
High frequency response
Self-generating (no external power required for the sensing element)
Small size and rugged construction
Cannot measure static or very slowly changing variables
Sensitive to temperature fluctuations
Requires high impedance signal conditioning (charge amplifiers)
Vibration analysis
Dynamic pressure monitoring
Microphones and ultrasonic transducers
Piezoelectric materials exhibit 'high' sensitivity for dynamic events because even minute mechanical displacements induce measurable voltages.
Option A is incorrect as the sensitivity is high, not low. Option C is incorrect as the output is linear, not exponential. Option D is incorrect as the output is highly dependent on stress.
B is correct тАФ Piezoelectric transducers are known for their high sensitivity to dynamic mechanical inputs and a linear relationship between stress and voltage output.
Remember that piezoelectric sensors act as high-pass filters; they cannot measure constant DC inputs, which is a common trap in instrumentation exams.