The Presentation is on the Transducers and some daily used transducers used in our life.

1. TRANSDUCERS
A PRESENTATION BY
MAHAK PANDYA
19BME066
MECHANICAL MEASUREMENTS
AND METEOROLOGY
SUBMITTED TO : KRUNAL MEHTA SIR

2. TRANSDUCERS
Transducers are device which converts one form of energy to
another. Usually they convert a signal in one form of energy
to a signal in another. Basically, they are used in automation,
measurement and control systems where electrical signals are
converted to other signals. Hence, it can convert any quantity
to be measured into a usable electrical signals. These are
used by us in our daily life. Examples are Microphone,
Loudspeakers, Thermometers, Antennae etc.

3. MORE ABOUT TRANSDUCERS…
Transducer has basically two parts
• Sensing Element
• Transduction Element
• Sensing Element : the part which gives response to the physical
sensation. Its response depends on the physical phenomenon.
• Transduction Element : it converts the output of sensing element
into an electrical signal. Also known as “Secondary transducer”.

4. LET US DISCUSS FOUR MECHANICAL
TRANSDUCERS USED IN DAILY SCIENCE!!

5. 1. BIMETALLIC STRIP
A bimetallic strip is used to convert a temperature change
into mechanical displacement. The strip consists of two
strips of different metals which expand at different rates
as they are heated, usually steel and copper, or in some
cases steel and brass. The different expansions force the
flat strip to bend one way if heated, and in the opposite
direction if cooled below its initial temperature. The metal
with the higher coefficient of thermal expansion is on the
outer side of the curve when the strip is heated and on the
inner side when cooled.

6. The working of the bimetallic strip depends on the thermal
expansion property of the metal. The thermal expansion is the
tendency of metal in which the volume of metal changes with
the variation in temperature. Every metal has a different
temperature coefficient. The temperature coefficient shows the
relation between the change in the physical dimension of metal
and the temperature that causes it. The expansion or contraction
of metal depends on the temperature coefficient, i.e., at the
same temperature the metals have different changes in the
physical dimension.
BIMETALLIC STRIP CONSTRUCTION

7. PRINCIPLE
• The strip consists of two strips of different metals which expand at
different rates as they are heated, usually steel and copper, or in some
cases steel and brass. The strips are joined together throughout their
length by riveting, brazing or welding. The different expansions force
the flat strip to bend one way if heated, and in the opposite direction
if cooled below its initial temperature. The metal with the
higher coefficient of thermal expansion is on the outer side of the
curve when the strip is heated and on the inner side when cooled. The
sideways displacement of the strip is much larger than the small
lengthways expansion in either of the two metals.
• In some applications the bimetal strip is used in the flat form. In
others, it is wrapped into a coil for compactness. The greater length of
the coiled version gives improved sensitivity.

8. WORKING OF THE STRIP
A traditional thermostat has two pieces of
different metals bolted together to form what's called
a bimetallic strip (or bimetal strip). The strip works as a
bridge in an electrical circuit connected to your heating
system. Normally the "bridge is down", the strip carries
electricity through the circuit, and the heating is on. When
the strip gets hot, one of the metals expands more than the
other so the whole strip bends very slightly. Eventually, it
bends so much that it breaks open the circuit. The "bridge is
up", the electricity instantly switches off, the heating cuts
out, and the room starts to cool.

9. APPLICATION OF BIMETALLIC STRIP
• Temperature indication
Bimetals are used for temperature indication as in the spiral or helix actuated pointer thermometers. Such
thermometers help measure temperatures in offices, refrigerators, and even on aircraft wings.
• Temperature control
Bimetals are utilized as a means to control the temperature, as in room temperature thermostats. In such
devices, a bimetal blade holds a current-carrying contact point that is linked to a coupled static contact
point.
• Tube and pipe couplings
For cryogenic, non-magnetic, and nuclear applications where metal properties must be switched reliably,
bimetallic couplings are used to enable direct connection and transition for pipes and tubes with different
CTEs.
• Function Control
By introducing heat to a bimetal – or what is known as auxiliary heating – the function of a device containing
the bimetal can be controlled. Circuit breakers and time delay devices are examples of these devices.

10. Bimetallic strip used in thermometers

11. 2. MANOMETER
A manometer is a scientific instrument used to
measure gas pressures. Open manometers measure
gas pressure relative to atmospheric pressure.
A mercury or oil manometer measures gas pressure as
the height of a fluid column of mercury or oil that
the gas sample supports.

12. CONSTRUCTION OF MANOMETER
Attach the plastic tubing carefully around the length of the plank using the tube fasteners. Ensure the
tubing makes a smooth, even “U” bend around the end of the plank so that the tubing does not
become kinked.
Position the plank against a vertical surface, such as a board. Use the plumb bob to ensure the plank is
exactly vertical. Hammer a nail through the plank or use some other means to attach it securely to the
board.
Pour approximately 100 ml water into the beaker. Add enough dye to turn the water a bright red and mix
thoroughly. Pour the water carefully into the tube.
Place a measuring device on the side of the manometer on the opposite end of the expected pressure.
Line up the zero point of the measuring device with the surface of the liquid and attach it securely with
tape. The measuring device may be a ruler or graph paper, depending on the specific application.
Attach a source of positive pressure to one end of the manometer with an airtight seal. The pressure may
then be measured in inches of water.

13. WORKING PRINCIPLE
A manometer works on the principle of hydrostatic
equilibrium and is used for measuring the pressure
(static pressure) exerted by a still liquid or gas.
Hydrostatic equilibrium states that the pressure
at any point in a fluid at rest is equal, and its value
is just the weight of the overlying fluid.

14. WORKING OF MANOMETER
• In a closed manometer, a sample of gas is introduced into one end, which is then capped.
Then, a fluid of known density is poured into the other end. The fluid will stop moving
when the pressure of the gas trapped between the cap and the fluid together with the
pressure at the bottom of the fluid column on that side matches the pressure of air plus
the pressure of the fluid column on the open side.
• The height of the fluid on the open side will be higher on that side when air pressure is
less than the gas pressure and lower on the open side when the air pressure exceeds the
gas pressure. You can use this height difference to calculate the gas pressure.
• Since P = F/A = mg/A, m = ρV and V = Ah for a cylindrical tube (i.e., volume = area times
height), it can be shown that the pressure created by a vertical column of fluid is ρgh,
where h = height in meters. This pressure represents the positive or negative difference
between the gas pressure and atmospheric pressure.

15. APPLICATION OF MANOMETER
• It is used for low range pressure measurements.
• Extensively used in laboratories.
• Is used in Orifice meter and Venturimeter for flow
measurements.
• It is used for calibration of gauges and other instruments.
• It is used for measuring pressure drop in different joints and
valves.

16. A real manometer
The Manometer Diagram

17. 3. GYROSCOPE
• A gyroscope is a device used for measuring or
maintaining orientation and angular velocity. It is a spinning wheel or
disc in which the axis of rotation (spin axis) is free to assume any
orientation by itself. When rotating, the orientation of this axis is
unaffected by tilting or rotation of the mounting, according to
the conservation of angular momentum.
• Gyroscopes based on other operating principles also exist, such as
the microchip-packaged MEMS gyroscopes found in electronic
devices (sometimes called gyrometers), solid-state ring lasers, fibre
optic gyroscopes, and the extremely sensitive quantum gyroscope.

18. CONSTRUCTION OF GYROSCOPE
The gyroscope consists of a central wheel or rotor that is mounted in a
framework of rings. The rings are properly called gimbals, or gimbal rings.
Gimbals are devices that support a wheel or other structure but allow it to
move freely. The rings themselves are supported on a spindle or axis at one
end that, in turn, can be mounted on a base or inside an instrument. The
property of the rotor axle to point toward its original orientation in space is
called gyroscopic inertia; inertia is simply the property of a moving object
to keep moving until it is stopped. Friction against the air eventually slows
the gyroscope's wheel, so its momentum erodes away. The axle then begins
to wobble. To maintain its inertia, a gyroscope must spin at a high speed, and
its mass must be concentrated toward the rim of the wheel.

19. WORKING PRINCIPLE
The basic effect upon which a gyroscope relies is that an
isolated spinning mass tends to keep its angular position with
respect to an inertial reference frame, and, when a constant
external torque (respectively, a constant angular speed) is applied
to the mass, its rotation axis undergoes a precession motion at a
constant angular speed (respectively, with a constant output
torque), in a direction that is normal to the direction of the
applied torque (respectively, to the constant angular speed) .
External forces acting on the center of mass of the rotating part
do not affect the angular position of the rotation axis.

20. WORKING OF GYROSCOPE
• When the force is applied to the axle, the section at the top of the gyroscope will try to
move to the left, and the section at the bottom of the gyroscope will try to move to the
right, as shown. If the gyroscope is not spinning, then the wheel flops over, as shown in the
video on the previous page. If the gyroscope is spinning, think about what happens to these
two sections of the gyroscope: Newton's first law of motion states that a body in motion
continues to move at a constant speed along a straight line unless acted upon by an
unbalanced force. So the top point on the gyroscope is acted on by the force applied to the
axle and begins to move toward the left. It continues trying to move leftward because of
Newton's first law of motion, but the gyro's spinning rotates it.
• This effect is the cause of precession. The different sections of the gyroscope receive
forces at one point but then rotate to new positions! When the section at the top of the gyro
rotates 90 degrees to the side, it continues in its desire to move to the left. The same holds
true for the section at the bottom -- it rotates 90 degrees to the side and it continues in its
desire to move to the right. These forces rotate the wheel in the precession direction. As
the identified points continue to rotate 90 more degrees, their original motions are
cancelled. So the gyroscope's axle hangs in the air and precesses.

21. APPLICATION OF GYROSCOPE
Gyroscopes are used in compasses and automatic
pilots on ships and aircraft, in the steering
mechanisms of torpedoes, and in the inertial
guidance systems installed in space launch
vehicles, ballistic missiles, and orbiting satellites.

22. GYROSCOPE
GYROSCOPE SENSORS USED IN MOBILE

23. 4. SPRING BALANCE
Spring balances provide a method of mass measurement
that is both simple and cheap. The mass is hung on the
end of a spring, and the deflection of the spring due to
the downwards gravitational force on the mass is
measured against a scale. Because the characteristics of
the spring are very susceptible to environmental
changes, measurement accuracy is usually relatively poor.
However, if compensation is made for the changes in
spring characteristics, then a measurement inaccuracy
less than ±0.2% is achievable. According to the design of
the instrument, masses between 0.5 kg and 10 tonne can
be measured.

24. CONSTRUCTION OF SPRING BALANCE
Spring balance is a weighing device that utilizes the relation between the
applied load and the deformation of a spring. This relationship is usually
linear; i.e., if the load is doubled, the deformation is doubled. In the
circular balance, the upper ends of the helical springs are attached to the casing
and the lower ends to a crossbar that can move relative to the casing and to
which the load hook is attached. The pinion to which the indicating pointer is
attached is pivoted in the casing and meshes with the rack, which is pivotally
connected to the crossbar and is pressed into contact with the pinion by the
rack spring.
When a load is applied, the springs are stretched, and movement of the
crossbar with the rack attached rotates the pinion and the load-indicating
pointer. The dial is graduated in scale units that depend on the stiffness of the
springs: the stiffer springs have larger scale units and higher load capacity.

25. WORKING PRINCIPLE
A spring scale or spring balance or Newton meter is a type
of weighing scale. It consists of spring fixed at one end with
a hook to attach an object at the other. It works by Hooke’s
Law, which states that the force needed to extend a spring
is proportional to the distance that spring is extended from
its rest position.
Hooke's law states that the applied force F equals a constant k
times the displacement or change in length x, or F = kx. The value of
k depends not only on the kind of elastic material under
consideration but also on its dimensions and shape

26. WORKING OF SPRING BALANCE
There is a direct relationship between how much the spring extends and the
force required to extend it.
If we place a weight at the end of the spring there is a force applied to the
spring due to the weight. Hooke’s law says that the spring will then extend.
As it extends you can measure the force due to the weight by looking at the
scale.
The spring extension and force applied is indicated on the scale. a process of
applying various forces to it and measuring the amount it extends for each
unit of force. This enables us to calibrate it and create a scale which
indicates force.

27. APPLICATION OF SPRING BALANCE
Main uses of spring balances are to weigh heavy loads
such as trucks, storage silos, and material carried on
a conveyor belt. They are also common in science
education as basic accelerators. They are used when
the accuracy afforded by other types of scales can
be sacrificed for simplicity, cheapness, and
robustness.

28. SPRING BALANCE USED IN LABS
SPRING BALANCE USED IN
CONVEYOR BELTS TO JOIN

29. THANK YOU !!!