Question

What kind of ultrasound is produced by piezoelectric crystal?

• A. Sound wave ultrasound
• B. Electrical wave ultrasound
• C. Pressure wave ultrasound
• D. Simple ultrasound

Hint:

Remember that sound waves, including ultrasound, are mechanical waves. They propagate through a medium by causing particles of the medium to oscillate, creating regions of compression (high pressure) and rarefaction (low pressure). Hence, they are fundamentally pressure waves.

Answer 1

The Correct Option is A

Definition of Ultrasound?

Ultrasound refers to sound waves with frequencies higher than the human hearing range (typically above 20 kHz). These waves are used in various applications, such as medical imaging, industrial testing, and cleaning, due to their ability to penetrate materials and reflect off surfaces.

Understanding the Options

Let’s examine each option to determine what kind of ultrasound is produced by a piezoelectric crystal:

1. Pressure Wave Ultrasound

Pressure wave ultrasound is not a standard term in ultrasound technology. However, ultrasound waves are a type of longitudinal wave, where particles in the medium vibrate, creating areas of compression and rarefaction. These can be thought of as pressure variations in the medium (like air, water, or tissue). While this description is partially accurate, it’s not the most precise term for the type of ultrasound produced by piezoelectric crystals.

2. Electrical Wave Ultrasound

Electrical wave ultrasound is not a recognized term. Piezoelectric crystals generate ultrasound through mechanical vibrations caused by an applied electric field, not by producing electrical waves. The output is a sound wave, not an electrical wave, so this option is incorrect.

3. Sound Wave Ultrasound

Sound wave ultrasound refers to ultrasound as a type of sound wave, which is accurate. Ultrasound is a high-frequency sound wave that travels through a medium (like tissue or water) as mechanical vibrations. Piezoelectric crystals produce these sound waves by vibrating when an electric voltage is applied, creating the ultrasound used in applications like medical imaging (e.g., sonograms). This term aligns with the standard definition of ultrasound.

4. Simple Ultrasound

Simple ultrasound is not a technical term used in the context of ultrasound production. Ultrasound can vary in frequency, intensity, or application, but "simple ultrasound" is not a specific category. This option is too vague and not a standard classification.

Why Sound Wave Ultrasound is the Correct Answer

A piezoelectric crystal works by converting electrical energy into mechanical vibrations. When an alternating electric voltage is applied, the crystal vibrates at a high frequency, producing ultrasound waves. These waves are high-frequency sound waves, typically above 20 kHz, that propagate through a medium as longitudinal waves, creating areas of compression and rarefaction.

In medical or industrial applications, the ultrasound produced by piezoelectric crystals is used for imaging, cleaning, or measuring distances. The term sound wave ultrasound accurately describes the output, as ultrasound is fundamentally a type of sound wave.

For example, in an ultrasound machine used for pregnancy scans, the piezoelectric crystal in the transducer generates high-frequency sound waves that reflect off tissues and create images. These are not electrical waves, pressure-specific waves, or vaguely "simple" ultrasound—they are sound waves.

Why Not the Other Options?

• Pressure Wave Ultrasound: While ultrasound involves pressure variations, this term is not specific or standard for describing the output of piezoelectric crystals.
• Electrical Wave Ultrasound: Incorrect, as piezoelectric crystals produce mechanical sound waves, not electrical waves.
• Simple Ultrasound: Not a recognized term and too vague to describe the specific type of ultrasound produced.

A Simple Way to Remember

Think of a piezoelectric crystal as a tiny speaker: when you send electricity to it, it vibrates to create sound waves. These sound waves are ultrasound because they’re too high-pitched for humans to hear. So, the result is sound wave ultrasound.

Final Answer

The kind of ultrasound produced by a piezoelectric crystal is Sound Wave Ultrasound.