Question

Frequency response of capacitive transducers is

• A. \( \text{Low} \)
• B. \( \text{Medium} \)
• C. \( \text{High} \)
• D. \( \text{Zero} \)

Hint:

The frequency response of a transducer is crucial for dynamic measurements. A transducer with a low frequency response will not accurately capture rapid changes in the measurand, leading to signal distortion. For applications involving fast-changing phenomena (e.g., high-frequency vibrations), transducers with a high frequency response are required. Conversely, for slowly varying or static measurements, a low frequency response is often sufficient.

Answer 1

The Correct Option is C

To solve this problem, let's analyze the frequency response of capacitive transducers and how they perform under varying input frequencies.

1. What is Frequency Response?

The frequency response of a transducer refers to its ability to accurately reproduce or measure a signal across different frequencies. It indicates how the output of the transducer varies with the frequency of the input signal.

2. Characteristics of Capacitive Transducers:

Capacitive transducers rely on changes in capacitance to measure physical quantities like displacement, pressure, or humidity. The frequency response of these transducers depends on:

• Mechanical Construction: The mass and stiffness of the moving parts affect the natural frequency and damping.
• Electrical Properties: The RC time constant (due to resistance and capacitance) influences the high-frequency cutoff.

3. Frequency Response of Capacitive Transducers:

Capacitive transducers generally exhibit a high frequency response because:

• They have very low moving mass (especially in MEMS-based designs), allowing them to respond quickly to high-frequency inputs.
• There is no significant mechanical inertia or damping to limit their speed of response.
• They can measure dynamic changes effectively, making them suitable for applications like vibration sensing and acoustic measurements.

4. Analysis of the Given Options:

The question presents four options for the frequency response:

1. High: This is correct because capacitive transducers can operate effectively at high frequencies due to their low inertia and fast electrical response.
2. Medium: This is incorrect because capacitive transducers typically perform better than medium-frequency devices (e.g., some resistive sensors).
3. Low: This is incorrect because capacitive transducers are not limited to low-frequency applications (unlike inductive transducers, which may suffer from eddy current losses at high frequencies).
4. Zero: This is incorrect as it implies no response, which is not true for any functional transducer.

5. Why High Frequency Response Matters:

A high frequency response is crucial for applications like:

• Vibration and acceleration sensing (e.g., in MEMS accelerometers).
• Ultrasonic measurements.
• Fast dynamic pressure or displacement monitoring.

6. Final Answer:

The frequency response of capacitive transducers is High, making them suitable for high-speed and dynamic measurements.