Category: Physics Notes PPT

Do you know there are 24 time zones in the world? A time zone is an area where a uniform standard time is followed for all the purposes such as legal, commercial, social etc and where the entire region regulates their clocks and time according to a standard time. These are generally defined as offsets from the UTC i.e. Coordinated Universal Time. In this article, we will be talking about the standard time. We will learn what is standard time and other aspects related to this such as EST time, time UTC, PST, PDT, CST, MST, etc that will help you to understand the concept of standard time.

Introduction

Time is considered as a continuous event that occurs in succession and follows a path of past, present and future where the events that have occurred in the past will never come back and talks about ongoing events in the present and succeed towards the future events. It is an ongoing process. Due to the rotation and shape of the Earth, all places of the world don’t receive sunlight at the same time which leads to making a difference in morning, evening and night in all the places because of which we need different time zones. That is why Earth is divided into 24 time zones according to which all the localities of that zone follow a uniform standard time.

Meaning of Standard Time

In a particular geographical region, the synchronisation of the clocks with respect to a single time is called a standard time rather than following the local mean time standard. Generally, the standard time is based on some longitude which usually passes through the centre of the region or the country and all the clocks of the region regulate their timings with respect to this longitude or meridian. 

History

In 1869, the usage of time zones was proposed by Charles F. Dowd according to which localities of the zone will use the same time and then Sir Standard Fleming and others also advocated this idea. In 1883, time zones were adopted by the US and Canada railroads. In 1884, Greenwich Royal Observatory at 0° was adopted as the meridian of transit in the International Conference held at Washington DC. The adoption of 24 time zones was done with those whose boundaries were defined by the local authorities. DST i.e Daylight saving time was adopted during World War I in various countries to save fuel in order to reduce the requirement of artificial light in the evening hours, the clocks were kept ahead or advanced by one hour.

Time UTC

UTC is an abbreviation used for Coordinated Universal Time. It is considered as the primary standard time according to which the countries of the world regulate their time and clocks. In simple words, it works as the basis for civil time today. The other names of this are Universal Time Coordinated and Universal Coordinated Time. It is a successor of GMT i.e. Greenwich Mean Time. It is fixed and no usage of daylight saving time is done here. It is located at 0° longitude i.e Prime Meridian and sea these are 7.5° West and East longitudes. This standard time is kept by the usage of atomic clocks which are combined with the rotation of the Earth. 

What about GMT?

It is an abbreviation for Greenwich Mean Time. It is also used as a basis for the countries of the world to regulate their clocks and timings. It is a clock time at Royal Observatory, Greenwich, London and this time means solar time that is counted from midnight. Sometimes it is used as a synonym of UTC but nowadays it is just a time zone, not a time reference. And it is equal to UT1 which means solar time at 0° but it can differ with respect to UTC by up to 0.9s. It is often used by the countries associated with the United Kingdom. 

EST Time

EST Time is an abbreviation used for Eastern Standard Time or Eastern Time. It is a standard time which is 5 hours behind the UTC i.e. Coordinated Universal Time in Autumn/Winter whereas it is 4 hours behind the UTC when observing the daylight saving time in Summer/Spring. EST time zone time is observed in some parts or all of the 23 states of the Eastern US, eastern parts of Canada, Quintana Roo state in Mexico, Panama, Columbia, Ecuador, Peru, some parts of western Brazil, Caribbean and Atlantic islands. 

PST Timing

It is an abbreviation for Pacific Standard Time or Pacific Time. It is behind UTC by eight hours whereas it is behind by 7 hours when observing daylight saving time. It is observed in some parts of western regions of Canada, the  US, and Mexico. DST which is Daylight Saving time is used in this zone. In this zone, when standard time is used it is called PST i.e Pacific Standard Time whereas when daylight saving time is used it is called PDT i.e. Pacific Daylight Time. Los Angeles is the largest city in this time zone.

CST

It is an abbreviation used for Central Standard Time or Central Time which is found in North America. It is observed in some parts of the US, Canada, Mexico, Central America, the Eastern Pacific Ocean and the Caribbean islands. Current time CST can also be used with respect to the UTC. When standard time is used it is 6 hours behind the UTC whereas when daylight saving time is used it is 5 hours behind the UTC. Mexico City is considered the largest city in this time zone. It is denoted by CST and CDT depending upon whether daylight saving time is used or not. 

Sometimes, CST abbreviation is also used for China Standard Time and Cuba Standard Time which must not be confused with Central Standard Time. If we talk about China standard Time, it is ahead by 8 hours whereas Cuba Standard time is behind by 4 hours from the UTC. 

Time in MST

MST is an abbreviation used for Mountain Time Standard in North America. This time is based on the mean solar time at the 105th meridian which is observed west of Greenwich. It is also called Mountain Time ( MT ). It is observed in the US, Canada and Mexico. When standard time is used it is 7 hours behind the UTC whereas when daylight saving time is used, it is considered as 6 hours behind the UTC. This time zone is observed as in the east of Pacific Time and west of the Central Time zone in the US and Canada.

Sometimes, MST abbreviation can be used with respect to the standard time of any country or region such as Malaysian Standard Time which is also abbreviated as MYT. This is ahead by 8 hours from the UTC.

Fun Fact

The international date line works as a boundary between two consecutive calendar dates and works as a  line of demarcation between them. It was established in 1884 and it is a  line that passes through 180° longitude from North to South. The interesting thing about it is that when you cross this line to the west, the date will forward by one means you will gain a day whereas when you travel to the east, you will lose a day. 

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Conclusion

Thus, to conclude we can say that the world is complex and the time of all different regions are much complex. In order to synchronise the clocks of a particular region or a country, standard time is used whereas the clocks and timings of the world are regulated by the time UTC. With respect to UTC, different time zones can be found in the world and standard time is followed by the regions or countries as per their requirements and it is generally based on the longitude that passes through the centre of the country according to which clocks of the entire region or country regulate their timings. In this article, we have talked about standard time and its history and other related aspects which are important to understand this concept which has a vital role in da
ily lives and whenever we study about time in Physics, Geography, Earth Sciences or Geology, etc.

Streamline flow or a laminar flow is an uninterrupted flow (as of air) past a solid body in which the direction at every point remains unchanged with the passage of time.

Streamline flow is a type of flow of fluid which travels in regular paths. So, we can say that there is a smooth movement of layers of water passing from one end of the pipe to another. So, when you look at a stream flowing, you first observe a few things about it like the speed of the water in it, its width, amount of water flowing, etc. One of the primary things that characterize a stream is its flow which is also termed as streamflow. This page discusses the streamline flow, various applications explaining this concept in detail.

What is a Streamline Flow?

A liquid or fluid motion happens when shear stress acts on it. This shear stress or force is acting parallel to the surface of the liquid. In the case of a stream flowing, the gravitational force of the earth is acting upon it and pulling it down.

Streamflow is described by a single atom’s path in a fluid and is of two types: streamline flow and turbulent flow. A flow that is steady, smooth, and predictable is called streamline flow. Sometimes the flow of a stream could be marked by chaotic changes that we call a turbulent flow. Let us learn about streamline flow definition and distinguish between streamline and turbulent flow in this article.

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Principle of Streamline Flow

A streamline flow is also called laminar flow, and in this flow, there are no major velocity fluctuations. A streamline is a path of imaginary particles within the fluid that are carried along with it. The streamlines are fixed in a steady flow, and fluid travels in a smooth and regular path. This means that the flow properties like velocity, pressure, etc. at each point remain constant. To define streamline flow, think of the laminar flow consisting of laminae or thin layers, all parallel to each other. In a streamline motion, these layers of water are flowing on top of each other at different speeds, and there is no mixing between layers.

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If you draw a tangent to the streamline at any point in space in a streamline flow, it will be aligned with the instantaneous velocity vector at that point. These streamlines cannot cross each other at any one instant in time. The fluid in contact with the surface is stationary, and the other layers are sliding over it.

Now, let us understand another type of flow, called the Turbulent flow. Also, we will understand the difference between Turbulent and Streamline flow.

What is Turbulent Flow?

A turbulent motion in a fluid is an irregular motion caused either by high velocities or abrupt changes in velocities. If you imagine a ball in a river stream, can you predict its direction of motion? It is probably not because water is splashing all around and the ball could go any which way every second. It is similar to the turbulent flow of fluids where there are random and unpredictable fluid particles’ motions. In a turbulent flow, fluid is not passing in parallel layers, and there is a high level of lateral mixing and disruption between layers.

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The three main characteristics of a turbulent flow are:

• Eddies

• Recirculation

• Apparent randomness

At any given point in the fluid which is undergoing turbulent flow, there is a continuous change in magnitude and the direction of flow. In our bodies, blood flow is generally streamline or laminar. But in certain high flow conditions, laminar flow can get disrupted and result in a turbulent flow. The flow in large arteries at the branch points are also turbulent flows. 

The streamline flow vs turbulent flow table below sums up the difference between streamline and turbulent flow:

Distinguish Between Streamline Flow and Turbulent Flow

Reynold’s Number

Reynold’s number is a dimensionless number that has a vital role in predicting patterns in a fluid’s behaviour. Reynold’s number is represented as Re, and it is used to determine whether fluid has a laminar or turbulent flow. Re is the ratio of forces of inertia (forces that tend to resist motion) to simple viscous forces (the intermolecular glue which holds the fluid together). At high values of Re, there is turbulence.

Re = inertial force/viscous force = (ρ * v * L)/𝜇

Where ρ is the density, v is the velocity, L is the diameter of the tube, and 𝜇 is viscosity.

It could also be expressed as:

Re =  fluid & flow properties/fluid properties.

 

So if there is a glass of water in a jar at rest then flow properties are 0. Thus, the numerator in the above equation is 0, which means that fluid at rest is independent of Reynold’s number. When the jar is tilted, and water starts flowing, we can predict water flow using Reynold’s number.

Resistance is the obstacle to the flow of electrons in the material. When a potential difference is applied across a conductor, it helps for the movement of the electrons while resistance opposes the movement of the electrons. A combination of those two factors is the rate at which charge flows between two terminals.

When a voltage is applied across a substance, an electrical current is produced. The voltage applied across the substance is, through it, directly proportional to the current.

V∝I

The proportionality constant is called the Resistivity of metals resistance.

V=RI

Hence resistance is defined as the ratio of the voltage applied through the substance to the current. Resistance is measured in ohms(Ω).

 

Unit of Resistance

From the concept of resistance, the unit of electrical resistance may be said to be volt per ampere. One unit of resistance is resistance which allows one unit of current to flow through itself when one unit of potential difference is applied to it. The unit of resistance per volt per ampere is called ohm(Ω).

 

The Resistance of Different Materials

1. Conductors: Those materials which offer very low resistance to the flow of electrons. Silver is a good electricity conductor but due to its high cost, it is not commonly used in electrical systems. Aluminum is a good conductor and is widely used as a conductor due to its low cost and abundance of availability.

 

2. Semiconductors: Materials that have a moderate value of resistance (not very high and not very low) at room temperature are known as semiconductors. There are several uses of semiconductors like for making electron devices. Silicon, germanium, are two materials mostly used for semiconductors. 

 

3. Insulators: Those materials which offer very high resistance to the flow of electrons. These materials are very bad electricity conductors and are mainly used in electric systems to prevent leakage current. Mica, porcelain, paper, dry wood, mineral oil, Nitrogen gas, air, etc are some good examples of insulators.

 

Resistance vs Temperature

The general rule says that resistance increases in conductors with increasing temperature and decreases with increasing temperature in insulators. In the case of semiconductors, typically, the resistance of the semiconductor decreases with the increasing temperature. But there is no simple mathematical relation to describe this relationship between resistance and temperature for different materials with graphs.

• For Conductor: The valence band and conduction band overlap with one another in the case of a conductor. So, a conductor’s conduction band contains excess electrons. By absorbing the energy, more electrons will go from the valence band to the conduction band when you raise the temperature.

• For Semiconductor: The conductivity of the semiconductor material increases with temperature increases. As temperature increases, outermost electrons acquire energy, and thus by acquiring energy, the outermost electrons leave the atom’s shell.

 

What is Resistivity?

Resistivity is basically the quantitative value of the resistance offered by any material. Although materials resist electrical current flow, some are better than others to conduct it. Resistivity is a figure that allows comparisons of how different materials allow or resist current flow.

The SI unit of resistivity is ohm⋅meter (Ω⋅m), commonly represented by the Greek letter ρ, rho.

The resistivity of a material can be defined in terms of the resistance (R), length (L), and area of the material (A). 

ρ=RA/L

From the equation, it can be seen that the resistance can be varied by adjusting a number of parameters.

 

Resistivity vs Temperature

The resistivity of materials depends on the temperature as ρt = ρ0 [1 + α (T – T0). This is the equation that shows the relationship between the resistivity and the temperature. 

ρt = ρ0 [1 + α (T – T0)

• ρ0 is the resistivity at a standard temperature 

• ρt is the resistivity at t0 C 

• T0  is the reference temperature

• α is the temperature coefficient of the resistivity

Here is the relationship between the resistivity and the temperature with graphs.

1. For Conductors: It is said that conductors have a positive co-temperature-efficient for metals or conductors. The positive value is α. For most metals, the resistivity increases linearly with temperature increases of around 500 K.

2. For Semiconductors: The resistivity of the semiconductor decreases with the increasing temperature.  It is said that they have a negative temperature coefficient. The temperature coefficient of resistivity, α, is therefore negative.

3. Insulators: For insulators, as the temperature increases, the material conductivity is increased. When the material’s conductivity increases, we know that the resistivity decreases, and the current flow increases thereby. And certain insulators convert to conductors at high temperatures at room temperature. They have a negative temperature coefficient. 

 

Fun Facts

The main reason for the resistor as an electrical component is to resist electricity. 

The value of a resistor is easily measured by an ohmmeter or multimeter.  

The study of electricity and power in physics is the most interesting chapter if the related concepts and formulas are understood well. The website explains the flow of current and its resistance power very beautifully and naturally so that the students can understand them easily. The experts have curated special videos on how the entire thing works and have explained the concepts so very well. Students can just refer to these materials available online and prepare well for their exams.

Resistance is defined as a measure of the opposition to the flow of current induced by voltage in an electrical circuit. Resistance is measured in ohms, s
ymbolized by the Greek letter omega (Ω). A force, such as friction, operates opposite the direction of motion of a body and tends to prevent or slow down the body’s motion. A simple example of resistance would be a child fighting against her kidnapper or the wind against the wings of a plane.

If you know the total current flowing and the voltage across the whole circuit present in any particular area, you can find the total resistance using 

Ohm’s Law: R = V / I.

For example, a parallel circuit has a voltage of 9 volts and a total current of 3 amps. The total resistance RT = 9 volts / 3 amps = 3 Ω.

Resistance vs Temperature

As the temperature rises, the number of phonons increases, and with it the likelihood that the electrons and phonons will collide. Thus when the temperature goes up, resistance goes up. For some materials, resistivity is a linear function of temperature. The resistivity of a conductor increases with temperature.

In 1920, a neutron was first theorized by Ernest Rutherford and then discovered by an English Physicist named James Chadwick in 1932. Therefore, Chadwick was awarded the Nobel prize in physics for the discovery of the same in the year 1935. 

A Thermal Neutron is a neutron that is in thermal/warm balance with the surrounding medium. 

These sorts of neutrons have a neutron speed of 2200 m/s at surrounding temperature states of 293.6 Kelvin relating to energy of 0.0253 eV.

On this page, you will find all the information on three different parameters of a thermal neutron, viz:  thermal neutron energy, thermal fission, and kinetic energy of thermal neutrons.

Thermal Neutron Definition

A thermal neutron or a free neutron (one that isn’t bound inside a nuclear core) has an average energy of movement (kinetic energy) in comparison to the average energy of the particles of the encompassing materials.

Moderately slow and of low energy, thermal neutrons show properties, like enormous cross segments in parting, that make them attractive in certain chain-reaction applications. 

Moreover, the long de Broglie frequencies of thermal neutrons make them significant for specific uses of neutron optics. 

Thermal neutrons are created by hindering more enthusiastic neutrons in a substance called an arbitrator after they have been launched out from nuclear cores during atomic reactions like fission. This process is also known as thermal fission.

Thermal Neutron Formation

Neutron is a subatomic particle arranged inside the core of the iota. It is electrically neutral (for example chargeless particles) and has a mass marginally higher than that of the proton. 

Neutrons, along with protons, are called nucleons. At the point when the neutron stays inside the core, it remains exceptionally steady and can be ousted by atomic change as it were. In any case, when a neutron stays outside the core, it turns out to be profoundly flimsy/unstable and goes through radioactive decay into a proton, an electron, and an antineutrino with the half-existence of around 10 minutes. Such a neutron is called the free neutron. 

This free neutron has a few applications, the most eminent one is the inception of the nuclear fission reaction. In parting, the heavier core parts into at least two lighter cores when the previous one is barraged by the high-speed neutrons.

In light of the energy of the free neutron, it very well may be characterized into a few gatherings – each gathering comprises reach-in neutron energy. Cold neutrons, Thermal neutrons, Cadmium neutron, Slow neutron, Fast neutron, and so forth are not many gatherings of free neutrons having various scopes of energy.

Here, we are focusing on a thermal neutron, so let’s discuss its properties in detail:

Properties of a Thermal Neutron

• A thermal neutron stays in warm harmony with the surrounding particles at Normal Temperature and Pressure (NTP). This shows the average kinetic energy of thermal neutrons is the same as that of any gas atom at 20°C.

• A free thermal neutron has energy in the request for 0.025 eV (minor deviation conceivable).

• The velocity of a thermal neutron is approximately 2.2 km/s.

Prompt neutrons delivered in nuclear fission are fast neutrons. Accordingly, a moderator is needed in thermal reactors to hinder the prompt neutron speed with the goal that such neutrons can initiate further fission to support a chain reaction.

Now, let us understand the concept of thermal energy:

Thermal Energy of Neutron

Quantitatively, the thermal energy per particle is approximately 0.025 electron volt. It is a measure of energy that relates to a neutron speed of around 2,000 meters each second and a neutron frequency of around 2 × 10-10 metres (or around two angstroms). 

Since the frequency of thermal neutrons relates to the normal spacings between atoms in glasslike/crystalline solids, light emissions neutrons are ideal for researching the design of precious stones, especially for finding places of hydrogen atoms, which are not very much situated by X-ray diffraction methods. 

(Thermal Neutrons Use)

Thermal neutrons are needed for initiating atomic parting in normally happening Uranium-235 and in misleadingly delivered Plutonium-239 and Uranium-233.

Kinetic Energy of Thermal Neutron Formula

According to Maxwellian distribution theory, the kinetic energy of thermal neutron distribution is Maxwellian, which is given by the following kinetic energy of  thermal neutron formula:                  

E = 12mn v2

The number/quantity of neutrons of energy “E” per unit energy span “N (E),” and the quantity of neutrons “v” per unit velocity interval, can be expressed as;

dN0/dE  =  N (E) = (2πN0)/(πkBT)3/2  [sqrt{E}]e-E/kBT                               

Here, kB is Boltzmann’s constant, whose value is 8.617333262 x 10-5 eV/K or 1.38 x 10-23 J/K. 

There’s a device that detects the thermal neutron presence, and that is a thermal neutron detector, let’s understand it:

Thermal Neutron Detector

A detection/Identification of neutrons is very specific since the neutrons are electrically neutral particles, hence they are chiefly dependent upon strong nuclear forces yet not on electric forces. Thus neutrons are not straightforwardly ionizing and they have generally to be changed over into charged particles before they can be distinguished. 

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By and large, every kind of neutron detector should be furnished with a converter (to change neutron radiation over to basic recognizable radiation) and one of the regular radiation detectors are a scintillation detector, gaseous detector, semiconductor detector.

Now, let’s have a look at some FAQs on our main topic, Thermal Neutron:

During a musical performance, we all love to judge the voice of singers. At this moment, we get more attracted to a magical musical voice. A person maintaining a good pitch and intensity is heard the most. The same scenario can be explained in Physics.

So, a voice timbre is the quality of the musical sound or a human voice (vocal timbre). So, if there are two or more sounds with the same frequency, the melodious one is a timbre. 

Define Timbre

In the musical world, timbre is known as tone colour or tone quality under the field of psychoacoustics. It is also recognized as the colour or the quality, and tone of a sound that makes it unique.

We define timbre as the heard sound quality of a musical note, sound, or tone. Timbre can distinguish several sound productions, such as choir voices, musical instruments, string instruments, wind instruments, and percussion instruments. 

Timbre also enables listeners to distinguish different instruments in the same category (same pitch and frequency). 

What is Timbre?

Let’s suppose that you and your friend compete in a music competition. You like to play Casio and your friend loves to play the guitar. However, you are good at making various beautiful tones that mean the tune quality is higher as compared to your friend. While your friend has a melodious voice than yours.

In the first scenario, your musical tones have good quality, while your friend has a good tone quality.

So, timbre considers a melodious sound coming from your instrument. Here, the good sound coming out of your musical notes is timbre.

Timbre also considers the melodious human voice. This category of timbre is vocal timbre or a voice timbre.

If you are a; singer, you know that a breathy sound is created by putting a lot of air behind each note as you sing.

Some examples of timbre are the ways used to express the sound, so terms like Flat, Light, Smooth, Smoky, Breathy, and Rough are what you use to differentiate one sound from another. How you recognize various sounds or voices you hear is attributed to the timbre (voice timbre).

So, from the above example, we understood that there are different types of timbre. Let’s understand these one-by-one:

Different Types of Timbre

The different types of timbre are as follows:

• Hamonic – A concert where all the musicians are playing their instruments in the same rhythm. 

• Polyphonic – In this case, independent musical parts overlap.

• Monophonic – In this scene, a single musical line is played.

• Accompanimental – It means accompanying a good quality.

Voice Timbre

If you look at the above context, it explained to you the real-life application of a timbre. As a singer, it is crucial to understand the different types of vocal timbre. We also call these the five-voice types. Now, let’s understand different types of timbre in voice timbre:

• Soprano – These singers sing in very high octaves.

• Mezzo – These singers sing in the middle range.

• Alto – Alto is the lowest of the female voices. 

• Bass – It is very broken up by high and low voices.

• Tenor – It is a male voice type.

• Contralto – We consider this voice as a middle voice.

• Treble – It is a word for a child’s voice.

These are also known as vocal timbre because they help us to identify various voices coming through a medium with the same frequency.

Dark Timbre

A novice person singing with a low voice is considered to have a dark timbre. We generally consider these terms in situations where a singer uses a low voice while singing at a concert for the first time in public.

However, dark tone is considered as the dark timber, whereas pop or rocky music is considered the light tone or the light timbre.

So the way you use your mouth can vary or alter the sound that is projected from your voice.

Timbre in Music 

You might have seen that musicians create varying timbres based on both their instrument and the number of frequencies the instrument creates.

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You must have noticed that each note from a musical instrument is a complex wave comprising more than one frequency. So, the way you play an instrument affects its timbre.

In simple words, an experienced guitarist will have timbre, and for a starter, timbre would require some time. Henceforth, building a timbre requires the experience of playing an instrument.

Timbre in Music Example

One of the illustrative examples of timbre in music is “attack and decay.” When you pluck a guitar string or strike piano keys, the sound hits forcefully; it is loud and then after some time, the voice of the music dies away.

The above-mentioned concept of timbre in music explains how the same note can have a different timbre when played differently by another musician.

Do You Know?

Your voice has its own timbre. The unique soundwaves you produce while speaking is what ables you to be easily recognized by others.

We know that when a spring is stretched from one end to another, it tries to come back to its original orientation. It happens because there is an interatomic force of attraction between the molecules tightly packed in the solid material like a spring. 

Now, when we exert force on these molecules to bring them away from their lattice points, they recover their position and spring regains its shape. 

Now, if the same helical spring is extended by a load, we can find the value of spring constant of helical spring by performing the helical spring experiment and this article discusses the same.

What is a Helical Spring?

A helical spring is the most commonly used mechanical spring in which a wire is wounded in a coil that seems like a screw thread. It is designed to carry, pull, or push loads. 

We can find the usage of the twisted helical or torsion springs in engine starters and hinges.

Now, let’s study how we can use the helical spring to do a spring constant experiment.

Helical Spring Experiment 

Aim of this Experiment:

Our objective is to find the force constant of the helical spring by plotting a graph between load and extension.

Apparatus or Materials Required:

Desired Diagram of Our Experiment:

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Theory of Spring Constant

If F is the force applied, x is the displacement of the spring, whose magnitude equals the magnitude of the force applied. The equation form is:

               F ∝ x

Here,

               F = – k x

This means ‘k’ is the force constant and the regaining is specified with a negative sign. A force constant or the spring constant ‘k’ has no unit.

Basically, spring has the formula mentioned in equation (1). Since we are here to find the force constant of helical spring by plotting a graph between load and extension, so instead of using the displacement term, we will use a length by which a helical spring got an extension under the influence of the load.

Here, we have the following equation:

                 F = kL

L = extension in the length of the helical spring, which is positive by nature.

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Procedure of the Experiment:

1. Suspend the helical spring from a rigid support and attach the pointer vertically and the hook from its lower free end. Hang a 40 g hanger from the hook.

2. Arrange the vertical wooden scale in such a way that the tip of the pointer comes over the divisions on the scale and can slide over it accordingly without touching it.

3. Firstly, add a dead weight to the hanger by keeping the spring vertical. Jot down the reading on the scale and record it in the loading column against the zero loads.

4. The weights of the range 20 g to 50 g are added one by one to the slotted weight to the hanger till the maximum load is reached. In each case, when the tip of the pointer moves down, note the reading of the pointer.

5. Then, each weight is removed one by one and the reading of the pointer is noted in each case of unloading.

6. Now, wait for some time till the pointer comes to rest. Repeat step 3.

7. As the pointer moves up. Repeat step 5 and 6 and record the reading in the unloading column.

8. Repeat step 7 till the only hanger is free.

9. Record your observation and perform the helical spring experiment calculations.

 

Helical Spring Experiment Calculations

1. The average of the readings for each load/weight during the loading and unloading process is calculated in each case.    Let m0, m1,m2, m3…etc.., be the average readings of the pointer for the loads w0, (w0 + 50), 

(w0+ 100), (w0+ 45), etc.

2. From this, extension, ‘L’ (in m) for the loads (w0 + 50), (w0+ 100), (w0+ 150), etc. , are calculated as (m1 – m0), (m2 – m0 ), (m3  – m0), respectively.

3. In each case, k = mg/l is calculated. 

4. Here, g is the acceleration due to gravity = 9.8 ms-2.The average value of k gives the helical spring constant in N/m.

Now, after making the helical spring experiment calculations, record these in the following table:

 

Value of Spring Constant of Helical Spring

Graph for the Helical Spring Constant Experiment

After performing all the experimentations, we get the following graph:

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OX = ——— kg wt

OY = ——— m

Value of spring constant of helical spring ‘K’ =  ——— Nm⁻¹

 

Result

By calculation, the value of the spring constant of helical spring is = ………….N/m.

From the helical spring load-extension graph, the force constant of the helical spring =……….N/m.