Ultrasonic wave notes

Topic includes

- Ultrasonic wave

- Visibility

- UV rays 

- Properties of Ultrasonic

- Application

- Sonar 

Ultrasonic wave

-Ultrasonic wave (UV) is electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency of approximately 30 PHz) to 400 nm (750 THz), shorter than that of visible light but longer than X-rays.

-UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun.

-It is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights.

- Consequently, the chemical and biological effects of UV are greater than simple heating effects, and many practical applications of UV radiation derive from its interactions with organic molecules.

Visibility

-  Ultravioletrays are invisible to most humans. The lens of the human eye blocks most radiation in the wavelength range of 300–400 nm; shorter wavelengths are blocked by the cornea.

 - Humans also lack color receptor adaptations for ultraviolet rays. Nevertheless, the photoreceptors of the retina are sensitive to near-UV, and people lacking a lens perceive near-UV as whitish-blue or whitish-violet.

 - Under some conditions, children and young adults can see ultraviolet down to wavelengths of about 310 nm.

 - Near-UV radiation is visible to insects, some mammals, and birds. Small birds have a fourth color receptor for ultraviolet rays; this gives birds "true" UV vision.

UV rays production

Ultraviolet radiation is produced by high-temperature surfaces, such as the Sun, in a continuous spectrum and by atomic excitation in a gaseous discharge tube as a discrete spectrum of wavelengths. ... Of the ultraviolet that does reach Earth's surface, almost 99 percent is UVA radiation.

Some examples of ultraviolet light

Ultraviolet Light. Ultraviolet light is a form of radiation which is not visible to the human eye.

It's in an invisible part of the "electromagnetic spectrum".

 Radiated energy, or radiation, is given off by many objects: a light bulb, a crackling fire, and stars are some examples of objects which emit radiation.

 Ultraviolet waves detection

Ultraviolet light causes our skin to freckle, tan, or sunburn. A safer way to detect UV light is with a UV detector. ... These beads are called UV detectors. They can use them to look for UV light around the school.

Such materials can block UV rays

Type of Material: Synthetic fabrics like nylon and polyester do a good job of blocking UV.

 Bleached cotton is a poor barrier material.

What color is best for sun protection?

Dark or bright colors

Darker colors absorb more UV than lighter colors like whites and pastels. But bright colors such as red can also absorb UV rays. The more vivid the color, the greater the protection—a bright yellow shirt is more protective than a pale one.

Piezoelectric effect

-Piezoelectricity is the electric charge that accumulates in certain solid materials (such as crystals, certain ceramics, and biological matter such as bone, DNA and various proteins) in response to applied mechanical stress.


- French physicists Jacques and Pierre Curie discovered piezoelectricity in 1880


- Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress. The word Piezoelectric is derived from the Greek piezein, which means to squeeze or press, and piezo, which is Greek for “push”.

What is the piezoelectric effect and how does it work?

Piezoelectricity (also called the piezoelectric effect) is the appearance of an electrical potential (a voltage, in other words) across the sides of a crystal when you subject it to mechanical stress (by squeezing it).

Is piezoelectric AC or DC?

A vibrating piezoelectric device generates an ac voltage while electrochemical batteries require a dc voltage, hence the first stage needed in an energy harvesting circuit is an ac–dc rectifier connected to the output of the piez
oelectric device

Application Of Drilling Machine:

The wide range of applications of drilling machines include :

• Origination and / or enlargement of existing straight through or stepped holes of different diameter and depth in wide range of work materials – this is the general or common use of drilling machines

• Making rectangular section slots by using slot drills having 3 or four flutes and 1800  cone angle

• Boring, after drilling, for accuracy and finish or prior to reaming

• Counterboring, countersinking, chamfering or combination using suitable tools.


Cold welding or contact welding is a solid-state welding process in which joining takes place without fusion/heating at the interface of the two parts to be welded. Unlike in the fusion-welding processes, no liquid or molten phase is present in the joint.

How does sonar work?

Sonar is simply making use of an echo. When an animal or machine makes a noise, it sends sound waves into the environment around it. Those waves bounce off nearby objects, and some of them reflect back to the object that made the noise. It's those reflected sound waves that you hear when your voice echoes back to you from a canyon. Whales and specialized machines can use reflected waves to locate distant objects and sense their shape and movement.

What are three uses for sonar?

Non military uses of sonar include fish finding, depth sounding, mapping of the sea bottom, Doppler navigation, and acoustic locating for divers

What is the principle of sonar?

Sonar is based on the principle of reflection of Ultrasonic Sound waves. Ultrasonic sound waves are high frequency waves with frequency over 20Khz. The SONAR transmitter in the Ship sends the ultrasonic sound waves towards the sea bed from where they get reflected. ... SONAR stands for Sound Navigation and Ranging.