Laboratory 1st Practical.
Laboratory 1st Practical.
Safety First when in Laboratory Environment.
Always come to Laboratory wearing closed shoes (preferably steel capped).
Open toes shoes or thongs are not allowed in the Laboratory
Lab coat is not essential, but if you have a Lab coat, please wear it.
Avoid overly bulky or loose-fitting clothing or dangling jewellery.
Pin or tie long hair and roll up loose sleeves.
With some common-sense rules in Laboratory, you can make the Laboratory safe not only for yourself but also for your colleagues around you.
Eating, drinking or smoking are not allowed in the Laboratory.
Leave the area clean and the equipment stacked neatly on the bench.
Aims of 1st Lab Practicals
Understand the basic principles and concepts related to measurement.
Be familiar with the instruments used for measurement including Laser measuring device and carryout measurements using those instruments.
Be familiar with the experimental layout and set-up for Friction measurement.
Written By:
Dr. Mahfooz Soomro
What is measurement and why it is important?
Measurement is a process of quantification of how large or small a physical quantity is, compared to a reference quantity of the same kind.
Or, measurement is a process of comparison of an unknown quantity with a known or standard quantity.
Measurement is important for standardisation.
Difference between metre and yard.
Metre and yard, both are the units of measurement, and are used to measure length, distance and height etc. The meter has basically been the base length unit in the SI or (System Internationale) of Units (mainly used in Europe). It is often called the length of the path which is traversed by light when in a vacuum.
Conversion
If you are involved in the real estate sector, you will never tire of converting metre to yards and vice versa.
Conversions into other units, the following should be noted:
1 meter is equal to 1.0936 yard
1 meter is 39.370 inches
1 centimetre is 0.39370 inches
1 millimetre is 0.039370 inches
1 yard is 0.9144 meters
1 inch is 0.0254 meters
1 yard is 36 inches
1 inch is 2.54 centimetres or 25.4 millimetres
Another rule of thumb is that a meter is almost 3 feet 3 3/8 inches which can work out to 0.125 mm.
Examples
The area of parking lot is 12 m2 and 500 cm2. Find the total area?
Solution:
1 cm2 = 0.0001 m2, or 1m2 = 10000 cm2
Therefore,
500 cm2 = 0.05 m2 and the total area = 12 m2 + 0.05 m2 = 12.05 m2
Jill wants to surround her garden on all four sides with fencing. Her rectangular garden is 270 cm by 130 cm. How many metres of fencing will she need?
Answer: 3.51 m2
What is 40 metres in yards?
Answer: 43.76 yds.
Jack and Jill ran on a treadmill exactly for 90 minutes. Jacks treadmill showed he ran 18500 metres. Jills treadmill showed she ran 20 km. Who ran farther and how much?
Use of Laser to measure the distance
A laser distance metre can be used to calculate (measure) accurate distance. It works by shooting out a laser dot beam. This beam strikes the surface and reflects back to the device. The laser device then calculates the distance based on the rebound laser beam.
Most models can also calculate not only distance but surface area and volume from making multiple measurements. Other features include continuous measurement, minima & maxima readings, and height of a wall or building using an indirect measurement using Pythagoras. They can also do the conversion from metre to foot or inch. Expensive units can transfer data by Bluetooth or Wi-Fi as well.
Vernier Callipers
A calliper (also called pair of calliper) is a device used to measure the dimensions of an object. Many types of callipers permit reading out a measurement on a ruled scale, a dial, or a digital display.
Diagram of Vernier Calliper
The labelled parts are
Outside large jaws: used to measure external diameter of an object (like a hollow cylinder) or width of an object (like a rod), diameter of an object (like a sphere).
Inside small jaws: used to measure the internal diameter of an object (like a hollow cylinder or pipe).
Depth probe/rod: used to measure depths of an object (like a small beaker) or a hole.
Main scale (Metric): marked every millimetre and helps to measure length correct up to 1mm.
Main scale (Imperial): marked in inches and fractions.
Vernier scale (Metric)gives interpolated measurements to 0.1mm or better.
Vernier scale (Imperial)gives interpolated measurements in fractions of an inch.
Retainer: used to block movable part to allow the easy transferring of a measurement.
These callipers comprise a calibrated scale with a fixed jaw, and another jaw, with a pointer, that slides along the scale. The distance between the jaws is then read in different ways.
The simplest method is to read the position of the pointer directly on the scale. When the pointer is between two markings, the user can mentallyinterpolate to improve the precision of the reading. This would be a simply calibrated calliper, but the addition of aVernier scale allows more accurate interpolation which is the universal practice.
Example:
Tell us the exact reading on the Vernier Callipers shown in the diagram?
Answer: 2.4735
Digital Calliper
Analog dial replaced with an electronic display that shows the reading as a numeric value. These callipers use a linear encoder. A linear encoder is a sensor or transducer. The sensor reads the scale in order to convert the encoded position into an analog or digital signal, which can then be decoded into position by a digital readout (DRO) or motion controller.
Micrometre
A micrometre, also called micrometre screw gauge, is a device incorporating a calibrated screw widely used for accurate measurement of precise linear measurements of dimensions such as diameter, thickness, and lengths of solid bodies, and components in mechanical engineering and machining as well as most mechanical trades, along with Vernier, and digital callipers.
Micrometres are usually in the form of callipers (opposing ends joined by a frame). The spindle is a very accurately machined screw and the object to be measured is placed between the spindle and the anvil. The spindle is moved by turning the knob or thimble until the object to be measured is lightly touched by both the spindle and the anvil.
Micrometres are also used in telescopes or microscopes to measure the apparent diameter of celestial bodies or microscopic objects.
Picture of digital micrometre.
Working Principle
Micrometres use the screw to transform small distances (that are too small to measure directly) into large rotations of the screw that are big enough to read from a scale. The accuracy of a micrometre derives from the accuracy of the thread-forms that are central to the core of its design. In some cases it is adifferential screw. Adifferential screwis amechanism used for making small, precise adjustments to the spacing between two objects
The basic operating principles of a micrometre are as follows:
The amount of rotation of an accurately made screw can be directly and precisely correlated to a certain amount of axial movement (and vice versa), through the constant known as the screw'slead. A screw'sleadis the distance it moves forward axially with one complete turn (360o).
With an appropriate lead and major diameter of the screw, a given amount of axial movement isamplifiedin the resulting circumferential movement.
For example, if the lead of a screw is 1mm, but the outer diameter is 10mm, then the circumference of the screw is 10, or about 31.4mm. Therefore, an axial movement of 1mm is amplified (magnified) to a circumferential movement of 31.4mm. This amplification allows a small difference in the sizes of two similar measured objects to correlate to a larger difference in the position of a micrometres thimble. In some micrometres, even greater accuracy is obtained by using adifferential screwadjuster to move the thimble in much smaller increments than a single thread.
Mass
The amount of matter contained in an object is known as its mass. The SI unit of mass is kilo-gram (kg).
1 gram (gm) = 1000 milligram (mg)
1000 grams = 1 kg
1000 kg = 1 tonne (t)
The mass of an object remains constant, irrespective of where it is at sea level, or on the mountain top, or in space.
Gravity
Gravity is a force that attracts a body towards the centre of the earth, or towards any other physical body having a mass. Every object that has mass exerts a gravitational pull or force on every other mass. The strength of this pull depends on the masses of objects.
Anything that has mass also has gravity. Objects with more mass have more gravity. Gravity also gets weaker with distance. So, the closer the objects are to each other, the stronger their gravitational pull is.
What else does gravity do?
Why do you land on the ground when you jump up instead of floating off into space? Why do things fall down when you throw them or drop them? The answer is gravity: an invisible force that pulls objects toward each other. Earth's gravity is what keeps you on the ground and what makes things fall.
Gravity isnt the same everywhere on Earth. Gravity is slightly stronger over places with more mass underground than over places with less mass.
Measuring Gravity
According to Newton, every object in the universe attracts every other object that is directly proportional to the product of the masses of the particles and inversely proportional to the square of the distance between them.
F = G m1.m2
r 2
F = gravitational force between two objects
m1 = mass of the first object
m2 = mass of the second object
r = distance between the centres of the two objects
G = universal constant of gravitation = 6.67 x 10-11 Nm2/kg2
Since the mass of the Earth is very large (5.98 x 1024 kg), that is why when an object is dropped from a height, it falls towards the Earth and not away from it.
The initial velocity of the object is zero m/s, but as the distance increases, the velocity of the falling object also increases. The rate of increase in velocity is called acceleration and in the case of free falling object, it is known as the acceleration due to gravity (g). The value of g is 9.807 m/s2 and can be approximated to 9.81 m/s2.
Example:
Find the gravitational force between the Earth and;An object with a mass of 1 kg.
A person with a mass of 80 kg.
Mass of Earth = 6.0 x 1024 kg
Radius of Earth = 6.4 x 106 m
G = 6.7 x 10-11 Nm2/kg2
F = G m1.m2
r2
6.7 x 10-11 x 6 x 1024 x 1 = 9.81 N
(6.4 x 106)2
6.7 x 10-11 x 6 x 1024 x 80 = 785.16 N
(6.4 x 106)2
Weight
The force with which an object is attracted towards Earth is called its weight. The force acting on the object due to Earths gravitational pull (or the weight of the object) can be calculated by the equation;F = m x g
Where m is the mass of the object (kg), and g is the acceleration due to gravity = 9.81 m/s2.
Example:
Weight of a 5 kg mass
F = m x g = 5 x 9.81 = 49.05 N
The weight of the body is not constant but changes slightly when we move from the Equator to the North Pole. Since, Earth is not a perfect sphere and bulges at the Equator. This affects the gravitational force which varies from 9.78 m/s2 at the Equator to 9.83 m/s2 at the North Pole.
1000 N = 1 kilo-newton (kN)
1000000 = 1 mega-newton (MN)
Volume
All substances, solids, liquids and gases occupy space, the amount of space occupied by an object is called its volume.
Volume = length x width x height or area x height (units m3, cm3 or mm3)
Density
If equal volumes of bricks, concrete, timber and other materials are compared, the values of their mass will be different; this is because different materials do not have the same density.
The density of a material is defined as its mass per unit volume.
2175924108038Mass
0Mass
212651290657Volume
0Volume
214718689609Density =
Units = kg/m3
The density of pure water is 1000 kg/m3. The density of a material is very important property and is used in several areas of building technology. For example, which materials (having lower density) should be used to reduce the load on the base of the house.
Example:
The mass of concrete block measuring 250 mm x 200 mm x 200 mm is 24.0 kg. Find the density of the concrete?
Solution:
250 mm/1000 mm = 0.25 m
200 mm/1000 mm = 0.2o m
Density = mass / volume = 24.0/0.25 x 0.20 x 0.20 = 2400 kg/m3
Example:
The cross sectional measurements of a 7.0 meter long concrete beam are 0.3m x 0.75m. Find the mass and weight of the beam. Density of the concrete = 2400 kg/m3.
Solution:
Volume of the beam = 7.0 x 0.3 x 0.75 = 1.575 m3
Mass = Density x Volume
= 2400 x 1.575 = 3780 kg
Weight = Mass x g
= 3780 x 9.81 = 37081.8 Newtons.
Specific Gravity
The specific gravity of a substance is defined as the ratio of the density of the material to the density of water.
Specific gravity = density of a material density of water
The specific gravity of a material remains the same, irrespective of the units of density.
The density of water at 4.0 oC = 1 g/cm3 or 1000 kg/m3
Friction
Friction is the resistance to motion of one object moving relative to another or it is a force that resists the sliding or rolling of solid surfaces, fluid layers, and material elementssliding against each other.
Factors Affecting Friction
Friction is a force that is dependent on external factors. Following are the two factors on which friction depends on the:
1. Nature of the two surfaces that are in contact
Friction is dependent on the smoothness or roughness of the two surfaces that are in contact with each other. When the surface is smooth, the friction between the two reduces as there is not much interlocking of irregularities. While the surface is rough, friction increases.
2. Force that is acting on these surfaces
Friction increases when the force is applied along with the irregularities.
What Causes Friction?
Friction is caused due to the irregularities on the two surfaces in contact. So, when one object moves over the other, these irregularities on the surface get entangled, giving rise to friction. The more the roughness, the more irregularities and more significant will be the friction.
Types of Friction
There are four types of friction and they are classified as follows:
Static friction
Sliding friction
Rolling friction
Fluid friction
Types of friction
Dry Friction
Static Friction
Static friction is defined as the frictional force that acts between the surfaces when they are at rest with respect to each other.
The magnitude of the static force is equal in the opposite direction when a small amount of force is applied. When the force increases, at some point maximum static friction is reached.
Examples of Static Friction
Skiing against the snow
Creating heat by rubbing both the hands together
Table lamp resting on the table
Kinetic Friction
Sliding friction is defined as the resistance that is created between any two objects when they are sliding against each other.
Examples of Sliding Friction
Sliding of the block across the floor
Two cards sliding against each other in a deck
Rolling Friction
Rolling friction is defined as the force which resists the motion of a ball or wheel and is the weakest types of friction.
Examples of Rolling Friction
Rolling of the log on the ground
Wheels of the moving vehicles
Fluid Friction
Fluid friction is defined as, the friction that exists between the layers of the fluid when they are moving relative to each other.
Examples of Fluid Friction
Following are the examples of fluid friction:
The flow of ink in pens
Swimming
Skin friction
Skin friction is a component ofdrag (air resistance on fast moving objects, cars, trains, trucks, boats etc.), the force resisting the motion of a fluid across the surface of a body.
Internal friction
Internal friction is the force resisting motion between the elements making up a solid material while it undergoesdeformation.
14922516065500
22682797945W
00W
240295721350800
163741489948R
R
2906188117786F
0F
18925952388042593842245893221043561462
2388545142875001431497156653
2253615181404N
0N
1601973258580030976192585800
The amount of friction between two surfaces depends on;The normal reaction, which acts at right angles to the two surfaces.
The roughness of the surfaces in contact.
The coefficient of friction () is given by
= Friction force or Resistance force (R) / Normal reaction between surfaces (N)
= R/N = F/W (R=F, N=W)
Example:
A horizontal force of 9.0 N moves a brick on a metal surface at a uniform speed. Fine the weight of the brick if the coefficient of friction between the two materials is 0.45.
Solution:
R = F = 9.0N; N = W
= R/N = R/W; therefore W = R/
W = 9.0 N/0.45 = 20.0 N
Example:
Calculate the force of friction acting on the object.
A 10 kg rubber block sliding on a concrete floor, where coefficient of friction () = 0.65.
Solution:
= R/N, where N= Weight of the rubber block
Force of Friction (R) = N
= 0.65 (10 kg x 9.8 m/s2)
= 637 Newtons
A 37 kg wooden crate sliding across a wood floor ( = 0.20).
Solution:
Force of Friction (R) = N
= 0.20 (37 kg x 9.8 m/s2)
= 72.5 Newtons
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Practical 2: Heat, light and sound in buildings
Building Science 2023
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This practical investigates the measurement of heat, light and sound in a room. The equipment used in this practical can measure temperature, humidity, windspeed, decibels (loudness), light intensity (lux), distance and direction.
Equipment
Sidchrome Non-contact Infrared Thermometer
Left standard tape measureRight Compass
Left Lutron LM-8102 5 in 1 Right Ozito Laser Range Finder
Thermal Comfort & Design
Thermal Comfort
35%
People can gain heat from the environment, through solar radiation or warm air. Heat is also continuously produced by the body. Most of the biochemical processes involved in tissue-building, energy conversion and muscular work generate heat. The deep body temperature must remain balanced and constant around 37oC. In order to maintain body temperature at this steady level, all surplus heat must be dissipated to the environment.
The body can release heat to its environment by convection, radiation and evaporation and to a lesser extent by conduction.
Convection dissipates heat from the body to air in contact with the skin or clothing. The warmed air rises and is replaced by cooler air. The rate of convective heat loss can be increased by air movement with a fan. Convective heat loss is also improved with a wide temperature difference between the body and environment; by lower air temperatures and/or higher skin temperatures.
The body can also radiate low-wavelength infra-red (i.e. invisible except with a thermal imaging camera) to its surroundings. Radiant heat loss depends on the body temperature and the temperature of adjacent surfaces. No radiation occurs if the surroundings are at the skin temperature.
Evaporation transfers latent heat through water vapour which is given out on the skin (perspiration) and in the breath (respiration). Evaporative heat loss is governed by the humidity of the air. Evaporation is limited if the air is saturated with water vapour (periods of high humidity). Conversely, evaporative heat loss can be enhanced by increased perspiration rates. The body elevates the amount of moisture available for evaporation.
In any thermal environment, it is difficult for more than half the occupants to agree that the conditions are comfortable. Our perception of thermal comfort is highly subjective. It is influenced by age, body shape, extent of clothing, even the mood and expectations of the occupants.
Ventilation Design
Ventilation in buildings is the process of changing the air in a room. Air flow provides oxygen for breathing and exhausts carbon dioxide. If ventilation is properly designed, it can cool the building occupants. Healthy conditions are also maintained if ventilation expels odours, vapours from cleaning solvents, furniture and building products, combustion products from heating and cooking and ozone gas from photocopiers and laser printers. Ventilation can reduce the build-up of water vapour that leads condensation and the growth of mildew and mould. Hence, air supply prevents disease by the removal of micro-organisms, mites, moulds and fungi.
The spent air must be replaced by an influx of fresh air. The fresh air must be heated or cooled which reduces the energy efficiency of the building. The provision of ventilation also impacts on other areas of building design. Airways allow the passage of fire and noise through the building.
Whether the thermal control of a building is accomplished by active or passive means, effective ventilation of the internal space is necessary to distribute heating or cooling without undesirable side-effects.
Passive forms of ventilation must allow for the behaviour of wind around a building. When wind strikes a building, a wedge-shaped mass of air builds up, which diverts air flow upwards and sideways. The wedge of air has a slightly higher air pressure than the general air mass.
As the wind diverges, a separation layer appears around the building. The wind tends to maintain its course so that the separation layers are re-combined behind the building. A low pressure region forms in front of the separation layers junction. The combined effect of the high pressure and low pressure zones causes a draught of air through the building. Ventilation of the building is hindered if the external pressure zones cannot form or the draught is obstructed inside the building.
This exercise investigates a series of poorly ventilated rooms. You are asked to suggest improvements to the ventilation of the space.
Procedure
You are required to assess the thermal quality of the practical rooms and the adjoining hallways.
Sketch the room dimensions and location of glass doors and windows.
Using either a mercury thermometer, the Sidchrome non-contact Infrared Thermometer and Lutron measure the temperature in several locations in the room, the wind speed and humidity.
Repeat this exercise in the adjoining hallway, approximately measure and sketch the hallway and measure the temperature in several locations, the wind speed and humidity.
Measure the conditions at any open exits.
Note air flow in the room and hallway.
Indicate on the diagrams the location of dead air zones.
What are your observations. Discuss this with the demonstrator. How does this help your understanding of thermal conditions related to temperature, humidity and airflow?
Suggest methods of improving the flow of air in the building.
Transmission of Heat
Heat impacts on a building in the form of solar radiation, high external air temperatures and internal heat sources. In most thermal designs, the heat flow is assumed to be constant. Under Australian conditions, the external air temperatures can vary up to 20oC from day to night. Temperature changes are accentuated by the effect of sunshine during the day. Heat flows into a building during the day and at night, during the cool period, the heat flow is reversed.
Heat flow through lightweight walls tends to vary with exterior temperatures. Conversely, high mass walls delay heat flow into and out of the building. During the day, the exterior face of a wall is heated by the sun. The temperature of the interior surface is not raised immediately because heat must be transmitted by conduction from particle to particle through the wall. The delay in heat flow depends on the thickness of the wall. For thick walls, the interior of the wall will heat up 6 to 10 hours after the exterior; the time lag effect. The passage of heat can be delayed into the late afternoon when the intensity of sunlight is reduced and outside of the wall is actually cooling. Heat flow may be reversed before the interior experiences the full effects of solar radiation on the building. The interior surface is never subjected to temperature swings as severe as the exterior; the decrement effect.
Periodic heat flow in a building
High mass walls also stabilize internal temperatures by heat storage. As heat transits through the wall, some of its energy is absorbed by the mass. In winter, walls that are subjected sunlight during the day, store heat and slowly release it during the evenings.
This exercise demonstrates the conduction of heat with various elements of a building envelope. We will be investigating the thermal response of different types of materials. For instance, heat flow through materials with high thermal mass, like brickwork, is delayed. The internal surface of a high mass wall is never subjected to the same temperature variations as the exterior.
Procedure
This experiment involves measuring the surface temperatures of walls and surfaces in the practical room with the non contact Sidchrome Infrared Thermometer. Investigate several materials including plaster, plastics and metal components.
Investigate various materials first by touch to your skin, notice how different surfaces feel colder or warmer than others.
Note the temperatures that have been recorded.
Consider why objects of similar surface temperature. What part does conduction have in this?
LIGHT IN THE BUILT ENVIRONMENT
The purpose of this exercise is to study light in the built environment.
Light Levels
In this study, the distribution of daylight and artificial light will be systematically measured and plotted. Any space must be designed for visual tasks while light levels are changing throughout the day. The effectiveness of the lighting scheme will be assessed both during the day and at night.
Illuminance levels in a room are influenced by indirect and direct factors. For natural lighting, the size of the windows directly affects the intensity of daylighting in the room. For artificial lighting, the intensity of luminaires determines light levels in a room. The layout of luminaires affects the distribution of light in the room. For instance, pools of light are created by concentrations of luminaires. The type of luminaire fitting can also determine the distribution of light in the room. For instance, lighting troughs reflect most of the light onto the ceiling so that a subdued, dark effect is created in the room.
Indirect factors also impinge on the quality of lighting in a space. The distribution of light in a room is determined by reflection of the light from the surfaces of the room, principally the walls. If the space is cavernous, wall reflection only constitutes a small proportion of the lighting. The resulting lighting distribution will be poor. Similarly if the walls are dirty or darkened (with wood paneling etc.) the space will appear dark and dingy because little light is reflected off the walls.
As well as the intensity of light, other qualities of lighting are also important in a room.
i) Colour Rendering. The colour temperature of the luminaires and the colour of the reflecting surfaces (i.e. walls) affects the perceived colour of the task or object. Monochromatic lights, like tungsten filaments, can distort the tint of an object and reduce colour contrasts between objects in the visual field.
ii) Modelling: Slightly directional lighting must be provided so that the observer can sense the three dimensional nature of an object.
iii) Glare Control: Lighting must be designed to avoid excessive contrast and over/under-illumination (discussed in Part B).
Equipment
Light meter (Model- LM 8102)
Laser distance measurement OR Tape measure
Adhesive Tape (optional)
1.Draw a sketch plan of the room. Note on the plan the location of doors, windows, luminaires (lights) and the colour and texture of all wall surfaces.
2.Using artificial light take horizontal illuminance readings at the grid points at the work plane height of the lab benches. If the readings vary at a point make an estimate of the average illuminance over 1 minute.
3.Ensure that the sensor is 300mm away from your body to avoid shadowing effects. Record the measurements at the grid positions on a plan.
4.Note how light is distributed in the room.
5.Record the illuminance level of daylight at the windows/glass doors of the room. The light meter must be held horizontal.
6.Repeat this exercise in the hallway and measure at 2 metre intervals.
What happens to light as you move away from natural and artificial light sources.
7.What are your observations of light distribution in a room.
Acoustic Phenomena
55 %
Introduction
The elements of a building (walls, floor and ceiling) exclude noise from a room. Noise must be kept below tolerable levels so that the activities within the building are not disrupted. The intensity of noise, that is permitted to enter a room, depends on the use of the space. Some activities, such as radio broadcasting, can only tolerate very soft sounds from the exterior.
Space Optimum dB(A)
Broadcast Studios 20-30
Conference rooms 35
Hospitals 35
Sleeping rooms 35-45
Libraries 35-45
Private offices 35-45
Classrooms 40
Theatres 40
Living rooms 40-45
Large offices 40-50
Restaurants 45
Noisy offices 50-60
Optimum Sound Levels
Reproduced from Greenland , J . (1993), Foundations of Architectural Science, p. 5/10.
Noise can impinge on a wall, floor or ceiling from an airborne-source or from a structure borne source, such as vibrating machinery or a physical impact. The enclosure elements must be designed and constructed to reduce the transmission of these noise sources.
Some of the noise can be reflected or re-radiated from the external face (Reflective reduction) while the rest of the sound energy is adsorbed. The adsorbed sound induces vibrations in the building envelope. Energy is lost initiating the vibrations (Mass reduction). Additional energy can be expended if the material is soft and hence has low stiffness. It is harder to propagate vibrations through a soft material, like lead (Flexibility reduction). The transmission of sound energy can be further minimised by introducing structural discontinuities (Insulating reduction).
Equipment
The basic set up of the equipment needed
Mobile Phone playing music (Noise Generator)
Sound Level Meter at bench height
Retractable Tape Measure
Lutron LM1802
Procedure
You are required to make measurements in the laboratory using the Lutron LM1802 sound meter function at 1 metre intervals from a noise source.
With several sound sources such as music or speaking measure the sound response in decibels with distance in one metre intervals in the practical room.
Measure the decibel levels in the corridor adjoining the practical room at 2 metre intervals measuring ambient noise.
How does sound in decibels decrease by distance.
Discuss this with your demonstrator.
