I will start discussion on this course, experimental physics-I.

This is the first lecture and I will give introduction about this course.

The concept we will cover in these lectures is basically, the aim of the course, the syllabus

of the course and the laboratory and the apparatus.

So, about them we will discuss in this lecture.

As you know, the aim of this course is: we want to learn about the experiments on physics.

there are many topics in physics and we will discuss on selective experiments.

We have designed the course in three modules: experimental physics-I: there we will discuss

experiments on mechanics, general properties of matter, thermal properties of matter, sound,

electricity and magnetism.

Then experimental physics-II: there we will discuss experiments on optics and modern physics

and experimental physics-III: in that module we will discuss experiments on solid state

physics and modern optics. each module is of 30 hours course and at present we will

discuss only module-I; module-II and module-III may be discussed in successive semester.

This course is not only for undergraduate students of physics; rather, it is compulsory

for all undergraduate students of science, engineering and technology, who have to deal

with instruments in any point of time during their carrier and profession.

In this course we will make you understand the working principle of common devices through

their applications in different experiments with particular aims; means in this course,

we will discuss different experiments, their different tools, different parts of apparatus

will be used and through application in those experiments, we will learn about the devices,

which will be frequently used in your carrier and in your profession.

As for example, all of you have seen the utility of the x-ray, MRI, CT Scan, Ultrasonography,

ECG, etcetera in hospitals and clinics.

Also if you look in any branch of science, whether in teaching laboratory, research laboratory,

industry, hospital, agricultural field, everywhere instruments are used for specific application.

To understand the basic principle of the instruments to handle the instruments efficiently and

even to think to design an instrument or experimental setup for specific application, this experimental

physics course will act as a foundation of the students apart from the degree in B.Sc,

M.Sc, BE, ME, B.Tech and M.Tech.

Also this course will have positive feedback for the national level examinations like GATE,

NET, JAM and JEST conducted by IIT, UGC CSIR, IIT and SERB, respectively.

Syllabus of this course, experimental physics-I: I will discuss about the basic analysis in

the laboratory.

When we will go to laboratory, you will perform experiment, specific experiment on different

topics in physics.

But there are common rules and regulations; there are some common things that everyone

has to know.

That is basically how to take data; how to analyze those data; where is the, what is

the source of error in the measurement; how we can minimize the error in the measurement;

how to calibrate the instrument; how to plot the data in graph.

And then after calculation you will get result; how to interpret that result and what are

the precautions in the laboratory.

This is a common phenomenon that I will discuss and then we will discuss some basic tools

in the laboratory.

There are tools, all the time you need them; you need these common tools; those are this

meter scale, slide calipers, screw gauge, magnifying glass, nut bolt screw and their

driver, galvanometer, ammeter, voltmeter, multimeter, cathode ray oscilloscope (CRO),

resistor, capacitor, inductor and so on.

These are the common tools, common components of any laboratory in science.

I will discuss about those basic tools.

And then we will go to the specific experiments.

We have selected some experiments, almost around 30 experiment, we have selected for

this experimental physics-I.

Those are the experiments on mechanics, general properties of matter, thermal properties of

matter and sound.

So, those experiments which we have selected that will be demonstrated in this course.

Determination of the restoring force per unit extension of a spiral spring, this is the

one experiment on mechanics.

You know the spring, spring has restoring force; if we extend it or compressed it, it

wants to go back in its original position, equilibrium position.

How to measure the restoring force per unit extension, that experiment will be performed.

We will demonstrate the second experiment: determination of the acceleration due to gravity

using compound pendulum; g, gravitational acceleration due to gravity, this is the universal

constant; how to determine this universal constant using the compound pendulum, that

experiment will be demonstrated.

Then third experiment: study the normal modes of oscillations of a compound pendulum and

measure the frequencies of this oscillation of a compound pendulum.

It has basically different modes: one mode is called normal mode.

What is the frequency of this normal mode, that experiment will be performed and we will

measure the frequency of the normal mode of the oscillation of the compound pendulum.

Then fourth experiment is the study of the free oscillation as well as forced oscillation

using Pohl pendulum.

This is another type of pendulum.

Using that pendulum, Pohl pendulum, we will measure the free oscillation and forced oscillation

of the pendulum.

It is basically in oscillation; you know, there is natural frequency of oscillation;

then, if you apply force on this oscillation externally, then it is a forced oscillation.

Another oscillation, we tell damped oscillation; means there is some resistance when it is

oscillating.

There are some resistance, those may be due to air, air resistance, some may be other

resistances due to eddy current, etcetera.

So, this is called damping; that is called damped oscillation.

Here we will demonstrate these free oscillation and forced oscillation using the Pohl?s pendulum.

Then fifth experiment: we will go for the study of transverse wave and longitudinal

wave.

You know the string; if we take a string and just you disturb it; then it oscillates.

So, that is the transverse oscillation, that we will study this transverse oscillation.

The longitudinal waves; this is the compressed of, say, when some waves are moving in the

air.

So, air, this is made of particles, air particles are compressed and elongated.

So, it is basically displaced along the direction, the waves are propagating that is basically

longitudinal waves.

we will demonstrate, we will study the transverse waves as well as longitudinal waves.

The sixth experiment, we will demonstrate, that is the determination of the moment of

inertia of a flywheel.

How to determine the moment of inertia of a body?

Here we will take this body as a flywheel and demonstrate, how to measure the moment

of inertia.

This way, there are some other experiments: seventh experiment: determination of Young

modulus of elasticity of a solid.

So, general properties of matter in this category.

We will demonstrate how to measure the Young?s modulus of elasticity of a solid, how to measure

the surface tension of a liquid, how to measure the viscosity of a liquid.

How to measure the thermal conductivity of a material, this is the thermal properties

of the matter; then linear expansion coefficient of a material.

Then we will demonstrate the next experiment: verification of Dulong-Petits law, this is

specific heat related experiment.

Then we will discuss, determination of the Stefan-Boltzmann constant of blackbody radiation.

These are the experiments on the heat.

Then next another experiment on heat: the experimental determination of Joule?s constant

J, that how to find out this Joule?s constant that will be explained.

Also we will perform and then some measurement on electricity.

Then the 15th experiment: variation of thermo EMF as a function of temperature and determine

the unknown temperature.

So, it is a thermometer, this is a thermocouple; using the thermocouple, how to measure the

temperature.

We will discuss physics behind this thermometer and then we will demonstrate, how to measure

the temperature, unknown temperature using this thermometer.

First we have to calibrate this thermo thermocouple; basically, due to the difference of the temperature

it generates EMF.

So, that is the thermal EMF, thermo EMF; temperature versus this thermo EMF that one has to calibrate.

After calibration, then you can find out any unknown temperature; that experiment we will

discuss.

Then another experiment of thermometer; as a thermometer this platinum resistance as

a function of temperature will determine the unknown temperature.

This is another thermometer, platinum resistance thermometer that also we will discuss.

Then experiment on sound; how to determine the velocity of sound in air medium.

You know this is measuring the velocity of light, measuring the velocity of sound.

So, these are the basic parameters.

How to measure this basic parameter.

In that group, one experiment we will discuss that is how to determine the velocity of sound

in air medium.

Then experiments on electricity and magnetism: determination of figure of merit of a dead

beat galvanometer.

When you are going to do experiment on this electricity, these galvanometer, voltmeter,

ammeter are the basic tools.

So, one should know about these basic tools, basic apparatus ok.

This is one experiment, which will make you familiar with the galvanometer, voltmeter,

ammeter.

What is the figure of merit and what it tells about the galvanometer?

So, we will discuss about the dead beat galvanometer and how to measure the merit figure of merit

of this galvanometer that experiment will be performed.

Then this, what is the, say current, sensitivity and charge sensitivity of a ballistic galvanometer.

The different kinds of galvanometers are there.

The dead beat and ballistic galvanometer are very useful for the lab.

We will first do the experiment to know about the dead beat galvanometer and ballistic galvanometer.

Then other experiments on electricity and magnetism are: the measurement of high resistance

using the capacitive discharge method, how to measure the resistance, resistance having

different range: say kilo Ohm, mega Ohm which we tell, it is a high resistance and then

if it is milliohm, micro Ohm: we tell it is very low resistance and then in between that

is some other resistance.

Here we will demonstrate, how to measure the high resistance, how to get the value of high

resistance.

There are different methods, but here we will use the capacity of discharge method and then

another experiment next for the low resistance: how to measure the low resistance?

We will use again it has different method, people use different method.

Here, we will use the method that is called Kelvin double bridge method.

Next experiment: how to measure the capacitance of a capacitor.

You know, these resistor, capacitor, inductor, these are the basic electric or electronic

components.

We should know about this basic components.

So, basically to know about these components, we will do some experiments to be familiar

with these basic components.

We will measure the capacitance of a capacitors and check the formulas for the capacitor,

capacitance of capacitors, when they are connected in series, when they are connected in parallel

and then we will study the charging and discharging of a capacitor and determine the time constant

of the capacitor.

Next experiment, we will do, the variation of the reactance of the L-R circuit.

So, reactance is the equivalent to resistance.

Resistance of the L-R circuit, LC circuit, it is a reactance, impedance, resistance.

So, these are equivalent depending on the combination of the circuit whether, it is

only R whether it is LR, whether it is LCR.

So, depending on that, this difference of impedance or reactance or resistance.

We will study the variation of reactance of the LR circuit with the frequency of the AC

source and determine the self inductance of an inductor.

The next experiment: we will study the resonance of LCR circuit and determine the Q-factor

of the circuits.

So, you will, say a circuit, quality of the circuit, it is determined measuring the Q-factor

of the circuit.

So, that experiment also we will do.

The next experiment, this as I told, is resistor capacitor inductor, these are the basic component.

Next component is inductor: we will study the variation of mutual inductance with the

angle variation between the two plane circular coils.

So, coil basically is the inductor; if you take 2 coils, interaction between these 2

coils; that is called mutual inductance.

So how mutually inductance varies when the angle between these 2 coils will vary, that

experiment we will perform.

This will give you or teach you about the inductor.

And then you know, when the current flows in a conductor, it generates magnetic field.

That type of experiment we will perform.

We will determine the magnetic field of a straight conductor as a function of current

and the distance from the conductor.

How magnetic field depends on the magnitude of the current, how magnetic field magnitude

of the magnetic field depends on the distance of the point where you want to measure the

magnetic field.

So, the distance of the point from the wire.

So, as a function of this current and distance we will measure the magnetic field when current

flows in a straight conductor.

Then we will study the variation of a magnetic field with distance along the axis of a circular

coil, when current will pass through the circular coil.

So, through circular coil, if you pass current through the circular coil, how magnetic field

varies that we will measure the magnetic field along the axis of the coil as a function of

the distance of the coil, as a distance of the point where we want to measure the magnetic

field from the center of the coil.

So, that experiment we will perform and I will show you how to generate magnetic field.

So, in our laboratory for different experiment, you will see that we will use the magnetic

field.

Say, you want to measure the magnetic field, want to measure the variation of resistance

of a material as a function of magnetic field; if we apply magnetic field, whether resistance

of the material changes; if changes, how it changes.

When you want to study this type of problem, you want to demonstrate this type of experiment,

you need magnetic field in the lab.

So, how to get the magnetic field in the lab, this is the way.

Then we use the electromagnet.

In electromagnet, 2 Helmholtz coils, we use to produce uniform field between these 2 coils.

So, in that uniform field we place of our material and then we vary the magnetic field

varying the current in the coil and then we measure the resistance of this material at

different magnetic field.

Here this is the basic experiment where you will learn how to generate magnetic field

in the laboratory.

This is the purpose to choose this experiments and then next experiment is a measurement

of the induced voltage in a coil as a function of magnitude and frequency of the current

in another coil producing magnetic field.

You know this law, this Faradays law, Faradays induction law.

If you have a coil, if you pass current through this coil, it will generate magnetic field.

Now, if you take another coils, if you take this coil without flowing current in this

coil, if you take this coil close to this coil, which is producing magnetic field.

This magnetic field is nothing, but the lines of force, magnetic lines of force.

So, this lines of force will pass through this second coil and so, that we tell this

flux this magnetic lines are passing through this and the second coil, we tell this flux

passing through the second coil and magnetic field is nothing, but the flux per unit area.

Now this coil, the second coil is in flux, is in magnetic field.

Now if there is a variation of the magnetic field or variation the flux linked with the

second coil, if it varies with time then there is a induced EMF produced, generated in this

second coil.

So, this induced EMF, it is basically proportional to the change of the rate of the flux.

So, if phi is the flux, d phi by dt that is the rate of change of the flux.

So, this induced EMF is basically equal to minus d phi by dt.

Why minus?

It is minus due to this EMF, induced EMF, there will be induced current in the coil,

second coil.

So now, due in this induced current in the coil, when current in the coil, it produce

magnetic field.

That magnetic field?s direction will be such that it will oppose this original magnetic

field.

That is why this minus sign is given.

So, it will oppose the magnetic field of the first coil.

In second coil, the direction of the EMF should be such that; that means, direction of the

current should be such that the second coil will produce magnetic field, induced magnetic

field, that filed will opposed the original magnetic field.

That is why it is the induced EMF which is equal to minus d phi by dt.

So, this is another very nice basic experiment that we will discuss and then we will discuss

the determination of Fourier spectrum, you know Fourier analysis of signals.

Any signal if it has one frequency that is fine; the most of the signals is not of one

frequency, is the superposition of the many frequencies.

So, Fourier analysis use to separate those frequencies.

There is the analysis of the spectrum, this is called: if we take any spectrum it has

different components of the frequency; now how to find out the different component of

the frequency in that spectrum.

There is a Fourier spectrum and that spectrum, we will determine the frequencies of the Fourier

spectrum in form of square wave, triangular wave or thus half sinusoidal waveform using

the CRO.

Again another basic instrument in the laboratory that is the CRO, cathode oscilloscope.

This is the basic instrument.

This experiment will help us to learn about the CRO.

So, we will do experiment and for each experiment, most of the experiment, there are some common

tools that will be used.

So, there is the application of these common tools in different experiments.

So, first I will discuss some basic tools and what are the basic tools that is what,

I told, it is a screw gauge and then slide caliper and then meter scale then volt meter

then galvanometer then CRO cathode ray oscilloscope, these are the basic instruments.

In most of the experiments, experimental setup, these tools are used, this apparatus are used.

Before I go to discuss this particular experiments wherever I showed you, I will discuss about

the basic instruments.

So those are the experiments we will discuss with time.

You have to go to laboratory, you need laboratory and then you need apparatus.

Now how should be the laboratory?

I think, students when go to the laboratory, somebody maintained the laboratory.

So, students do not bother about the laboratory; they get the readymade set up on the table

and they perform the experiments.

I think we have to look in different way.

You have to think, if you want to develop a laboratory, so how laboratory should be,

that if you have to think.

I believe that the laboratory should be well lighted room with humidity and temperature

control.

The room should contain cages or cupboards or a large closet in which the apparatus can

be stored when not in use; because, you have to save your setup and when you are fabricating,

generating, producing something, you have to take care saving them.

There should be some arrangement for keeping the apparatus, when they are not in use.

Then there should be table with power sockets for each experimental setup with sufficient

space surrounding the table and then there should be more common tools such as screw

driver set, a shouldering iron, a multimeter, a magnifying glass, meter scale slide, calipers,

screw gauge, galvanometer, voltmeter, ammeter, etcetera.

These are very common tools and it should be always available to the students.

Those should be close to the hand of the students.

There should be a small store with basic components such as this family of nut, bolt, screws;

family of wires; also family of resistors, inductors, capacitors, bread board, lenses,

mirrors etcetera.

These are the basic components and various kind of these components should be in the

laboratory; because, these are small components, anytime you may need them and it should be

available to you; there should not be wastage of time that it is not there.

If we need one screw and if screw is not there, you cannot do the experiment or what we want

to do that you cannot do immediately.

So, I think these are the basic components, which should be available in the laboratory.

These are the introduction about this course and then next we will discuss basic components

and some common tools in next class.

Thank you for your kind attention.