Define frequency and wavelength with reference to sound. Explain what is echo. Write full form of SONAR. Give any one application of ultrasound.

Frequency: In the context of sound, frequency refers to the number of cycles or vibrations of a sound wave that occur in one second. It is measured in hertz (Hz). The frequency determines the pitch of a sound, with higher frequencies corresponding to higher-pitched sounds and lower frequencies corresponding to lower-pitched sounds.

Wavelength: Wavelength is the distance between two consecutive points in a sound wave that are in the same phase (e.g., two crests or two troughs). It is usually represented by the Greek letter lambda (λ) and is measured in meters. Wavelength and frequency are inversely related: the higher the frequency, the shorter the wavelength, and vice versa.

Echo: An echo is a reflected sound wave that arrives at the listener's ear after bouncing off a surface or object. When a sound wave encounters a barrier, such as a wall or a cliff, a portion of the wave is reflected back towards its source. If the reflected sound wave reaches the listener's ear with a noticeable time delay and intensity reduction, it is perceived as an echo. The distance between the source of sound and the reflecting surface can be estimated by measuring the time it takes for the echo to return.

SONAR: SONAR stands for "Sound Navigation And Ranging." It is a technique that uses sound waves to navigate, communicate, and detect objects underwater. It works by emitting sound pulses into the water and then listening for the echoes that bounce back from underwater objects or the seafloor. By analyzing the time it takes for the echoes to return and their characteristics, SONAR systems can determine the distance, direction, and composition of objects or obstacles in the water.

Application of ultrasound: One of the applications of ultrasound is in medical imaging, specifically in the form of ultrasound scans or sonography. Ultrasound imaging uses high-frequency sound waves (above the range of human hearing) to produce real-time images of structures inside the body. It is commonly used to visualize the developing fetus during pregnancy, examine organs, tissues, and blood vessels, guide medical procedures, and diagnose various conditions. Ultrasound imaging is non-invasive, safe, and does not involve ionizing radiation, making it a widely used and valuable diagnostic tool in healthcare.