for Engineering Physics

1. Mahatma Gandhi Institute of
Technical Education And
Research CenterAssignment for Ultrasonic
Prepared by:
Purva Patel - 22
Sagar Patel - 23
Vaibhav Patel - 24
Feni Patel – 25
Deep Patel - 26
Jinal Patel – 27
CSE (I-SEM)

2. :::Questions:::
1)) Explain the theory of production of ultrasonic waves using
Magnetostriction Effect.
2)) Describe minimum 20 applications of Ultrasonic waves in
different fields.
3)) Describe the construction and method of measuring the
wavelength and velocity of ultrasound in liquid medium.
4)) How is the depth of sea measured using Ultrasonic waves?
5 )) Explain in detail Piezo-electric effect and piezo-electric
crystal

3. **Introduction**
The word ultrasonic combines the Latin roots ultra, meaning "beyond," and
sonic, or sound.. These sounds have applications for imaging, detection, and navigation
—from helping prospective parents get a glimpse of their unborn child to guiding
submarines through the oceans.
-:Review:-
---Ultrasonic refers to any study or application of sound waves that are higher frequency
than the human audible range. The field of ultrasonic thus involves the use of sound
waves outside the audible range for humans
---Music and common sounds that we consider pleasant are typically 12 kHz or less,
while some humans can hear frequencies up to 20 kHz.
---Ultrasonic waves consist of frequencies greater than 20 kHz and exist in excess of 25
MHz.
---Ultrasonic waves are used in many applications including plastic welding, medicine,
jewelry cleaning, and nondestructive test.
Within nondestructive test, ultrasonic waves give us the ability to “see through”
solid/opaque material and detect surface or internal flaws without affecting the material
in an adverse manner.

4. 1. Explain the theory of production of ultrasonic waves
using Magnetostriction Effect.
Principle:-
When a ferromagnetic material in the form of a rod is subjected to an
alternating magnetic field as shown in figure, the rod undergoes alternate
contractions and expansions at a frequency equal to the frequency of the applied
magnetic field –This phenomena is known as Magnetostriction effect.
Construction:-
The circuit diagram is shown in figure.
The ferromagnetic rod AB is clamped a the middle X. The coils L1 and L2 are
wound at the ends of the rod. To the coil L1 a variable capacitor connected in
parallel and this combination make tank Or resonant circuit. One side of this
tank circuit is connected to the anode of triode through ammeter. Other side is
connected to the cathode through a H.T. battery. L2 is connected Betn
the grid
and the cathode.

5. Ferromagnetic rod
N S
P
G
C
L2 L1
C1
+
-
L.T.
mA
X
xA B
Ultrasonic waves
P- Plate
C-Cathode
G-Grid
F-Filament
L.T.-Low tension
Battery
H.T.-High tension
Battery
F
Ultrasonic waves

6. Working:-
when the battery is switched on, the tank circuit L1C1 in the plate circuit
of the triode sets up an alternating current of frequency,
f = 1
2 √ L1C1
As a result rod gets magnetized by the plate current. any
change in current brings change in the magnetization A change in the
length of rod. this is gives flux in coil L2,thereby inducing an emf in the coil
L2. this emf is applied to the triode valve and is fed back to coil L2, so there
will be oscillations
These is varied by capacitor C1, the frequency of oscillation of
the tank circuit gets varies. If the tank frequency matches with the
frequency of natural frequency of the material then because of resonance
the rod vibrates with producing ultrasonic waves at the end of the rod. The
miliammeter gives maximum value of the resonance.
The frequency of ultrasonic produced by this method depends
upon the length l density ..and the elastic constant E of the rod.
i.e., f = 1 E
2l √ 

7. Advantages:-
1.The deign of this generator is very simple & cost is law
2.At low frequencies, large o/p is possible without the risk of damage to the oscillatory
circuit.
3.Frequencies ranging from 100Hz to 3000kHz.
Disadvantages:-
1.It can’t generate frequencies of ultrasonic greater than 3000kHz
2.The frequency of oscillation depends greatly on temperature.
3.There will be losses of energy due to hysteresis and eddy current.

8. 2 Describe minimum 20 applications of
Ultrasonic waves in different fields.
Science and engineering
1. It is used to detect flaws or cracked in metals.
2.It is used to detect ships, submarines, iceberg etc, in ocean.
3. It is used for soldering aluminium coil capacitors, aluminium wires and plates without
using any fluxes.
4. It is used to weld some metals which can’t be welded by electric or gas welding
5. It is used to cutting and drilling holes in metals.
6. It is used to form stable emulsion of even immiscible liquids like water and oil or water
and mercury which finds application in the preparation of photographic films, face creams
etc.
7.It act Like a catalytic agent and accelerate chemical reactions.

9. Medicine
8. It is used to remove kidney stones and brain tumours without shedding any blood.
9. It is used to remove broken teeth.
10. It is used for sterilising milk and to kill bacteria.
11. It is used to study the blood flow velocities in blood vessels of our body.
12. It is used as a diagnostic tool to detect tumours, breast cancer and also the growth of
foetus can be studied.
Another Uses:-
13 .A Cheap Ultrasonic Range Finder
Working-
Everybody knows the speed of the sound
in the dry air is around 340 m/s. Send a short
ultrasonic pulse at 40 kHz in the air, and try to listen
to the echo. Of course you won't hear anything, but
with an ultrasonic sensor the back pulse can be
detected. If you know the time of the forth & back
travel of the ultrasonic wave, you know the distance,
divide the distance by two and you know the range
from the ultrasonic sensor to the first obstacle in
front of it.

10. 14.Laser Ultrasonic Camera
Measurement of the characteristics of ultrasonic wave
motion, such as wave speed, attenuation and the presence of scattered
waves from microstructural features or flaws are used to perform NDE for
quality control. Laser ultrasonics refers to the process whereby lasers are
used for both generation and detection of ultrasonic waves in materials,
thereby providing a noncontacting method for performing ultrasonic NDE.
The current state of the art utilizes a pulsed laser for ultrasonic generation
through the process of thermoelastic expansion or weak ablation. The
method of detection involves interferometry of the Michelson, Fabry-Perot,
and Photorefractive (adaptive) types. Commercially available systems utilize
these interferometric methods and provide a "point and shoot" single point
measurement capability. In order to perform measurements over a large
surface, the laser generation and detection spots must be scanned in a
raster fashion over the area recording ultrasonic signals at each location.
The INL Laser Ultrasonic Camera directly images
(without the need for scanning) the surface distribution of
subnanometer ultrasonic motion at frequencies from Hz to
GHz. Ultrasonic waves form a useful nondestructive
evaluation (NDE) probe for determining physical and
mechanical properties of materials and parts. The reason
for this is that ultrasonic waves or "sound" can be
generated in all forms of matter: liquids, solids and gases
and exhibit information about the material in which they
travel.

11. 15.Ultrasonic Flow meters in Waste Water Plants
Introduction:-
Waste Water Treatment Plants require a
large variety of instrumentation in order to
monitor and control the processes in the different
stages. For the purpose of flow
metering; do electromagnetic flow meters and
ultrasonic flow meters offer the features and
performance which is demanded in these
applications.
The constituent parts of an ultrasonic flow meter are a hydrostatic pressure sensor
for measuring depth, a temperature sensor, and an ultrasonic transmitter/receiver pair for
measuring water velocity. These are all controlled by a data logger, which records data as
specified from the scheme created by the user software. A single cable links the submerged
instrument to a weather-proof polycarbonate enclosure which provides a data download point,
and where the battery is stored. The enclosure has an optional LCD display.
The flow meter is mounted on (or near) the bottom of the stream/pipe/culvert and
measures velocity and depth of the water flowing over it. Normally it is faced upstream and
reports positive flow but it is a bi-directional instrument capable of measuring

12. Chemical reaction
Other
Ultrasonic can also speed up certain chemical reactions. Hence,
it has gained application in agriculture, thanks to research which revealed
that seeds subjected to ultrasound may germinate more rapidly and
produce higher yields. In addition to its uses in the dairy industry, noted
above, ultrasonics is of value to farmers in the related beef industry, who
use it to measure cows' fat layers before taking them to market
Ultrasonic soldering implements the principle of
cavitations, producing microscopic bubbles in molten solder, a
process that removes metal oxides. Hence, this is a case of both
"binding" (soldering) and "loosening"—removing impurities from
the area to be soldered. The dairy industry, too, uses ultrasonics
for both purposes: ultrasonic waves break up fat globules in
milk, so that the fat can be mixed together with the milk in the
well-known process of homogenization. Similarly, ultrasonic
pasteurization facilitates the separation of the milk from harmful
bacteria and other microorganisms.

13. 3 Describe the construction and method of measuring the
wavelength and velocity of ultrasound in liquid medium.
Collimator
Sodium Lamp
Oscillator
d
Reflector
Telescope 1st
order maximum
1st
order maximum
Central maxima
Screen
A B
Q
Liquid column
The arrangement of experiment is shown in figure

14. Construction:-
The arrangement of experiment is shown in figure. There is a glass vessel
containing the liquid with a reflector R fixed within the vessel at its top.
A quartz crystal Q placed between two metal plates A and B is mounted at the
bottom of the plate vessel.
The metallic plates are connected to an oscillator whose frequency is adjusted that,
the crystal vibrates in resonance with the frequency of the oscillator and thus the ultrasonic
produce. thus the liquid behave like grating. This grating is put on the prism table of a
spectrometer and a parallel beam of light from the monochromatic source S is passed through
the liquid angles to the wave. Since, the liquid is behaving like a grating the light beam on
passing through it gets diffracted and produces a diffraction pattern. The pattern is viewed
through the telescope.
The diffraction pattern consists of central maxima with other maxima on both sides
like 1st
order maxima etc. If  is the angle of diffraction for the nth
order principle maxima then,
d sin = nwhere = wavelength of light which is used
d = grating element distance between adjacent nodal planes.
d = u
2 where u = wavelength of ultrasonic
therefore, u sin = n or u = 2n
2 sin 

15. When we know and n and by measuring  , we can know the wavelength of
ultrasonic.
If the resonant frequency of the ultrasonic generator is f; then the velocity of
ultrasonic waves through liquids and gases at various temperatures can be determined………

16. 4 How is the depth of sea measured using
Ultrasonic waves?
Ship
Receiving TransducerTransmitting Transducer
A BO
C

17. Sonar is a device which stands for Sound Navigation and Ranging.
By using SONAR, the distance and direction of submarines, depth of sea,
depth of rocks in the sea , the shoal of fish in sea etc can be determined.
also ultrasonic waves can be used to find the depth of the sea. It is based
on the principle of echo sounding.
The figure shows the use of ultrasonic to find the depth of the sea
The ultrasonic waves sent from the point A travel through sea water and get
reflected from the bottom of the sea. The reflected waves are received at the point B.
The time t taken for the ultrasonic wave to travel to the bottom of the sea
and to get reflected from bottom of the sea. The reflected waves are received at the
point B.
The time t taken for the ultrasonic wave to travel to the bottom of the sea
and to get reflected to the top surface is noted using a CRO. If the velocity of the
ultrasonic wave is already known; then,
Velocity v = Distance traveled
Time taken
v = AC+CB 2CO
t t
Therefore,
CO = Depth of the sea = v t
2
Thus ,the depth of the sea can be calculated using the formula
Fathometer or Echo meter is a device which is directly calibrated to

18. Q
----------
++++++
A
B
L2
L1C1
L.T.
H.T.
+
-
Triode
A
G
C
Ultrasonic
Ultrasonic
Secondary
L3
P
r
i
m
a
r
y
Piezoelectric oscillator method
Over view of piezoelectric method

19. 5 Explain in detail Piezo-electric effect and Piezo-
electric crystals.
+
+
+
+
+
-
-
-
-
-
Optic axis
Pressure
Pressure
X1 X2 X3 Electric axis
Y1 Y2 Y3 Mechanical axis
X1 X1
X2
X2
X3
X3
Y1
Y1
Y2
Y2
Y3
Y3

20. When pressure is applied to one pair of opposite faces of
crystals like quartz, tourmaline, Rochelle salt etc. cut with their
faces perpendicular to its optic axis , equal and opposite charges
appear across its other faces as shown in figure . This
phenomena is known as piezoelectric effect. The frequency of the
developed emf is equal to the frequency of dynamical pressure.
The sign of the charges gets reversed if the crystal is
subjected to tension instead of pressure.
The electricity produced by means of piezoelectric effect is
called piezoelectricity. The matter which can undergo
piezoelectric effect are called as piezoelectric materials or
crystals.
Piezo-electric effect

21. Thank You…