PIEZOELECTRIC EFFECT & ULTRASONIC WAVES | Physics 12| Ch 25 MEDICAL IMAGING | Lec 1| NBF| FBISE

PIEZOELECTRIC EFFECT & ULTRASONIC WAVES | Physics 12| Ch 25 MEDICAL IMAGING | Lecture 1| National Book Foundation| Federal board

In this lecture of Chapter 25 – Medical Imaging (Physics Class 12, National Book Foundation, Federal Board), we explore the Piezoelectric Effect and Ultrasonic Waves, two important topics in modern physics and medical technology.

The piezoelectric effect is the property of certain materials to generate an electric charge when mechanical stress is applied. When such a material (like quartz or lead zirconate titanate) is compressed, positive and negative charge centers shift, creating an external electric field. This phenomenon is reversible — applying an electric field can produce mechanical stress — known as the inverse piezoelectric effect.

This effect is widely used in devices that produce and detect sound, especially ultrasound transducers, where electrical signals are converted into mechanical vibrations. The resulting high-frequency vibrations generate ultrasonic waves — sound waves above 20,000 Hz, which are beyond human hearing.

Generation and Detection of Ultrasound:
Ultrasound is produced using the inverse piezoelectric effect. A piezoelectric crystal vibrates rapidly when an alternating voltage is applied, producing ultrasonic waves. When these waves hit an object, they reflect or scatter back to the transducer, causing vibrations that generate electric signals. These signals are processed to create an image, as used in medical ultrasound (sonography).

Applications of Ultrasound:
Ultrasound technology is a non-invasive and safe diagnostic tool used to image internal organs and monitor fetal development. It also aids in detecting tumors, cysts, and abnormalities within soft tissues. The method is harmless compared to X-rays, making it ideal for continuous monitoring.

Therapeutic and Industrial Uses:
Focused ultrasonic waves are used in neurosurgery, muscle therapy, and pain treatment (e.g., arthritis and rheumatism). In industry, ultrasonic flow meters use reflected sound waves to measure liquid flow and detect Doppler shifts, while Doppler ultrasound in medicine helps assess blood flow, detect clots, and evaluate heart and artery conditions.

Through the study of piezoelectric materials and ultrasound applications, students understand how mechanical and electrical energy are interlinked — a concept fundamental to medical imaging and modern instrumentation.

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Tags :

Physics 12, Piezoelectric Effect, Ultrasonic Waves, Medical Imaging, National Book Foundation, Federal Board, Class 12 Physics, Chapter 25 Physics, Physics Lecture, FBISE, Piezoelectric Transducer, Ultrasound Generation, Inverse Piezoelectric Effect, Sonography, Doppler Ultrasound, Ultrasound Applications, Ultrasound in Medicine, Ultrasound Therapy, Physics Practical, Sound Waves Physics