Non-Destructive Testing (NDT) Practice Test

What primarily determines the frequency of a transducer?

1. Length of the cable

2. Thickness of the piezoelectric element

3. Temperature of the material

4. Size of the transducer

The correct answer is: Thickness of the piezoelectric element

The frequency of a transducer is primarily determined by the thickness of the piezoelectric element. In piezoelectric transducers, the thickness of the material plays a critical role in defining the resonant frequency. Thinner elements generally produce higher frequencies, while thicker elements result in lower frequencies. This is due to the relationship between the speed of sound in the material and the physical dimensions of the piezoelectric element. When an electric voltage is applied to the piezoelectric element, it vibrates at its natural frequency determined by its thickness and material properties. This vibration generates ultrasonic waves, which are utilized in various applications, such as ultrasonic testing and imaging. The other choices focus on factors that do not directly influence the frequency of the ultrasonic signal produced by the transducer. For example, the length of the cable affects signal transmission but not the frequency of the transducer itself. Similarly, while temperature can influence material properties, it is not a primary determinant of the inherent operational frequency of a transducer. Lastly, the overall size of the transducer refers to its dimensions but does not specifically determine the frequency, which is more closely linked to the thickness of the piezoelectric element.