Category: Physics Notes PPT

Before we start with the electric dipole moment we must understand what do we mean by the term dipole and dipole moment. An electric dipole is a pair of equal and opposite charges separated by a considerably short distance. In an electric dipole, the magnitude of both the charges will be the same, we can not consider a pair of two charges with different magnitudes. 

Since an electric dipole is a pair of equal and opposite charges, therefore the total charge in an electric dipole will be zero. While studying electric dipole we should understand that the total charge of an electric dipole is zero does not mean that field of an electric dipole is zero.

Dipole Moment

Whenever two equal and opposite charges are brought together there will be either some attraction or repulsion force between them. Some examples of electric dipoles are HCl, H₂O, CH₃COOH, etc. These molecules will have fixed dipole moments because the center behavior center of the positive charge will not be coinciding with the negative charge. The electric dipole moment is a vector quantity, it has a specific direction and magnitude. The electric dipole moment physics plays an important role to understand the concept of polarisation. Now, let us define electric dipole moment, or in other words, let us have look at how do we define dipole moment of an electric dipole.

Define Electric Dipole Moment

Now, the dipole moment definition is given as the product of the magnitude of charges and the separation between them. The dipole moment determines the strength of an electric dipole to produce the electric field. It is denoted by P and it is a vector quantity.

Mathematically, the electric dipole moment is given by:

Consider two point charges q and -q place on dipole axis separated by a distance 2a, then the electric dipole moment is,

⇒ P = q x 2a………..(1)

Where,

q – The magnitude of the charge

2a – The separation between two charges

Equation (1) is known as the electric dipole moment formula physics.

The direction of the dipole moment is always from the negative charge to the positive charge. The SI unit of the electric dipole moment is Coloumb-meter(C-m). The dimensional formula of an electric dipole is

M⁰L¹T¹A¹

M⁰L¹T¹A¹.

Dipoles in an External Electric Field

Consider an electric dipole placed in an external electric field. The electric dipole will experience some force and is known as the torque. The torque is the force exerted on the dipoles placed in an external electric field and is given by,

⇒τ = P x E = PE Sin θ ………(1)

Where,

P – The dipole moment

E – The applied external field 

Significance of Electric Dipole and the Electric Dipole Moment

• The concept of an electric dipole is not only having importance in physics but it is an equally valid and prominent topic in chemistry as well.

• We know that most of the matter made up of atoms and molecules will be electrically neutral. Depending upon the behaviour of the pair of charges, the molecules are subdivided into two types,

• Polar Molecules: If the centre of mass of positive charge doesn’t coincide with the centre of mass of negative charge then it is known as a polar molecule.

• Non-Polar Molecules: If the center of mass of positive charge coincides with the center,  charges, s of negative charge then it is known as a Non-Polar molecule.

• Polar molecules possess permanent dipole moments. These dipoles are randomly oriented in the absence of an external electric field. On applying an electric field, the polar molecules will align themselves in the direction of the electric field.

• In a system, if the net charge is zero, that does not mean that there will be no electric field or the electric field will be absent. This was more evident by studying the electric dipole moment. Therefore, the study of an electric dipole is important.

• The study of dipoles and the dipole moments will help us understand the concept of polarization.

Example

1. When an Electric Dipole P is Placed in a Uniform Electric Field E, at What Angle Between P and E  the Value of Torque will be Maximum?

Ans: Given that an electric dipole is placed in a uniform electric field. We aim to calculate the maximum torque.

We know that the torque acting on a dipole placed in an external electric field is given by,

⇒τ = P x E = PE Sin θ ………(1)

Where, P – The dipole moment

E – The applied external field 

Therefore, the value torque will be maximum when the angle between the electric field and the dipole moment is 90⁰

Electrical Resistance is a barrier caused to the current flow in the circuit. 

While going to any special location with your family, you might have observed when your driver drives the car fastly, on encountering the obstruction on the road, he slows down the car. 

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However, during nights, when it is impossible to see the roads clearly while driving at pace, your car jumps with a high jerk suddenly.

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Do you know what this obstruction is? Well, this obstruction is the resistance, and when this obstruction occurs to the flow of current in an electric circuit, it becomes electrical resistance.

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In this article, we are going to discuss, what is electrical resistance and the factors that affect electrical resistance.

What is Electrical Resistance of a Conductor?

The electrical resistance of a conductor is the obstacle posed by the conductor to the current flowing through it. 

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We define the resistance of a conductor as the ratio of the potential difference ‘V’ applied across the ends of a conductor to the current ‘I’ flowing through its ends. The formula for the electrical resistance is: 

                           R = V/I

(The resistance is symbolized by a letter ‘R’)  

The S.I. unit of the resistance is Ohm, where:

1 Ohm = 1 Volt/ 1 Ampere = 1 V/1A

Thus 1Ω is defined as the resistance of a conductor through which one ampere of current flows through the conductor when a potential difference of 1 V is applied to its ends. 

The dimensional formula for the resistance is: [M1L2T-3A-2].

Factors Affecting Electrical Resistance of Conductor

The resistance of a conducting wire is because of the collision of free electrons in the conductor while drifting towards its positive end.

The resistance of a material viz:  wire, conductor depends on the following factors:

• Length of the material

• Area of the material

• Temperature

• Resistance on Increasing or Decreasing the Length

Consider two identical slabs of conductors each of length ‘l’ and cross-sectional area ‘A’. Let  ‘V’ be the potential difference applied across either of the slabs/conductors and ‘I’ be the current flowing through it.

So, the resistance of the conductor is:

                       R = V/I

Now, placing the two identical conductors side-by-side, the total length becomes l + l = 2l. If the same potential difference is applied across both the slabs, the current becomes I/2. The resistance of the arrangement becomes:

                         R’ = V/I/2 = 2V/I = 2R…..(1)

Equation (1) states that on doubling the length of the wire or any conductor, the resistance also doubles, i.e., R ∝ I.

Let’s consider a slab and cut it into two halves each of length ‘l’, and a cross-sectional area of ‘A/2’. When the potential difference is applied across the ends of a conductor and the current flowing through it is I/2, then the resistance becomes:

                     R’ = V/I/2  = 2 V/I = 2R…..(2)

Here, we can see from equation (2) that on dividing the conductor slab into two halves, i.e., on halving the area of cross-section of a conductor, the resistance doubles, therefore, R ∝ 1/A.

1. Conductors

Conductors have very low resistance. One must note that copper has very low resistance but its conductance is very high, that’s why copper is used as a connecting wire. While there are other conductors like gold and silver, they also conduct electricity.

If R is the resistance, then conductance ‘G’ is:

                      G = 1/R

2. Insulators

The resistance offered by insulators is very high. In between the conductor and the insulator, there are pure semiconductors, having very high resistance.

3. Alloys

Alloys like Manganin and Constantan offer low resistance, their smaller lengths are required for the wires of a given diameter in making the standard resistances.

• Temperature of the Material

When the temperature of the material increases, the thermal energy of the material also increases because of which ions/atoms of a conductor start vibrating with higher amplitudes and frequencies. 

As the free electrons start drifting towards the positive end of the conductor, the relaxation time reduces. This, in turn, increases the resistance of the conductor. 

If R0 was the resistance of the material at 0℃ and Rf is the current temperature, then the rise in resistance with the rise in the temperature by t℃ is given by:

                           Rf = R0 (1 + ∝t + βt2)

Here, ∝ & β are the temperature coefficients of resistance whose values vary from metal to metal. The unit of 1/K or 1/℃.

In practical applications, is given by:

∝ = [frac{R_{f}-R_{0}}{R_{0} times t}] = [frac{increase ; in ; resistance}{original ; resistamce times rise ; in ; temparature}]

So, we define temperature coefficient as the increase in resistance per unit original resistance per degree rise in temperature.

The temperature of is different for different temperatures. Now, if the temperature varies, i.e., if the temperature ranges from t1℃ to t2℃, then ∝ is:

             ∝ = [frac{R_{f}-R_{0}}{R_{0} times (t_{2}-t_{1})}]

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Electromagnetic waves of different frequency are termed by different names since they have different origin and effects on matter. In order of growing frequency and reducing wavelength these are microwaves, radio waves, visible light, ultraviolet radiation, infrared radiation, X-rays and gamma rays. EM waves are produced by electrically charged particles experiencing acceleration, and these waves can consequently interact with other charged particles, applying force on them. Electromagnetic waves carry energy, motion, and angular momentum away from their source particle and can impart those magnitudes to matter with which they interact. EM radiation is related with those electromagnetic waves that are free to transmit themselves (“radiate”) without the permanent influence of the moving charges that created them because they have attained sufficient distance from those charges. Therefore, Electromagnetic radiation is sometimes referred to as the far field. That means the near field denotes to EM fields close to the charges and current that directly created electromagnetic induction and electrostatic induction occurrences precisely.

How are Electromagnetic waves formed?

• Usually, an electric field is formed by a charged particle. A force is applied by this electric field on other charged particles. Positive charges speed up in the direction of the field and negative charges speed up in a direction opposite to the direction of the field.
• The Magnetic field is created by a moving charged particle. A force is applied by this magnetic field on other moving particles. The energy on these charges is constantly perpendicular to the direction of their speed and therefore only changes the direction of the speed.
• So, the EM field is formed by an accelerating charged particle. Electromagnetic waves are nothing but electric and magnetic fields drifting through free space with the speed of light. A speeding charged particle is when the charged particle oscillates about a symmetry position. If the frequency of oscillation of the charged particle is f, then it yields an electromagnetic wave with frequency f. The wavelength “λ” of this wave is written as λ = c/f. Electromagnetic waves passing energy through space.
• Electromagnetic waves are exposed by a sinusoidal graph. It contains time-varying electric and magnetic fields which are perpendicular to each other and are also perpendicular to the direction of transmission of waves. Electromagnetic waves are diagonal in nature. The graph is as shown below:

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Properties

Electrodynamics is the study of electromagnetic radiation, and EM is the physical phenomenon related to the concept of electrodynamics. Electric and magnetic fields follow the properties of superposition. Therefore, a field due to any precise particle or time-varying magnetic or electric field donates to the fields present in the same space because of other causes. Further, as they are vector fields, all magnetic and electric field vectors combine together according to vector addition. For i
nstance, in optics two or more coherent light waves may interact and by destructive or constructive interference produce a resultant irradiance differing from the total of the component irradiances of the individual light waves. 

Ever since light is an oscillation and it is not affected by migrating through magnetic fields or static electric in a linear medium like a vacuum. Still, in nonlinear media, such as certain crystals, interactions can happen between light and static electric and magnetic fields — these interactions contain the Kerr effect and the Faraday effect.

In refraction, a wave passing from one medium to another of different density changes its speed and direction upon arriving the new medium. The ratio of the refractive indices of the media regulates the degree of refraction. 

Electromagnetic radiation shows both particle properties and waves properties at the same time. Both particle and wave characteristics have been established in several experiments. Wave properties are more seeming when electromagnetic radiation is calculated over comparatively large timescales and over large distances while particle characteristics are highly evident when measuring small timescales and distances. For instance, when EM radiation is absorbed by matter, particle-like characteristics will be more obvious when a certain number of photons in the cube of the related wavelength is much smaller than one. It is not too difficult to experimentally detect non-uniform deposition of energy when the light is absorbed; still, this alone is not confirmation of “particulate” behavior. Rather, it reflects the significant nature of matter. Representing that the light itself is quantized, not just its interaction with matter is a more subtle affair.

Certain experiments show both the particle and wave natures of electromagnetic waves, like the self-interference of an individual photon. When a single or lone photon is passed through an interferometer, it passes through both paths, interfering with itself, as waves do, yet is noticed by a photomultiplier or other sensitive detector only once.

A quantum theory of the communication between EM radiation and matter such as electrons is defined by the theory of quantum electrodynamics.

Electromagnetic waves might be polarized, refracted, reflected, diffracted or interfered with each other.

Wave model

A vital aspect of light’s nature is its frequency. The frequency of a wave is the volume of oscillation and is calculated in Hertz, the SI unit of frequency, where 1 hertz = 1 oscillation per second. Light usually has multiple frequencies that sum up to form the resulting wave. Different frequencies endure different angles of refraction, a process known as dispersion.
A wave contains successive channels and crests, and the distance among two adjacent crests or channels is named the wavelength. Waves of the EM spectrum vary in size, from very lengthy radio waves the size of buildings to very small gamma rays minor than atom nuclei. Frequency is inversely proportional to wavelength. According to equation

V = f𝞴
In equation v is the velocity of the wave (c in a vacuum, or fewer in other media), λ is the wavelength and f is the frequency. As waves pass through boundaries among different media, their velocities change but their frequencies remain constant.

Electromagnetic Wave Equation:

(υ2ph▽2−∂2∂t2)B=0

Given, υph=1μ
ϵ√

Electromagnetic Wave Intensity:

I=PA=12cϵ0E20=12cμ0B20

The velocity of Electromagnetic Waves in Free Space:

It is written by C=√1(μ0ϵ0)

Given,

μ0 is termed absolute permeability. Its value is 1.257×10−6TmA⁻¹

ϵ0 is termed absolute permittivity. Its value is 8.854×10−12C2N−1m⁻²

C is the velocity of light in vacuum = velocity of electromagnetic waves in free space = 3×108ms−1

Electromagnetic Spectrum:

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Electromagnetic waves are categorized on the basis of their frequency “f” or according to their wavelength λ=cf.

Wavelength ranges of different lights are as follows,

For visible light – around. 400 nm to approx. 700 nm
For violet light – about. 400 nm
For red light – about. 700 nm

An electrostatic precipitator is also known in short form as ESP is a filtration device that removes fine particles that are like smoke or the dust. In contrast to all that we will discuss in this article which is wet scrubbers which apply energy directly to the flowing medium of fluid an ESP that applies 

In 1824 the first use which is of corona discharge that too to remove particles which are from an aerosol was by Hohlfeld. However we can say that it was not commercialized until almost a century later.

Note: Cottrell which is the first and is applied on the device to the collection of sulphuric acid mist and oxides of lead that fumes emitted from various acid-making and activities which are smelting as well.

Working Principle of Electrostatic Precipitator

At the time which is of Cottrell’s invention the basis which is theoretical for operation was not understood. The theory which is operational was developed later in the country Germany with the work of Walter Deutsch. And also the formation of the Lurgi company which he assigned the patents. The Goddard’s rocketry experiments by Lawrence’s cyclotron and the production methods for vitamins A and B1 which was among many others.

The  Lurgi Apparatebau-Gesellschaft which is in Germany and Japanese Cottrell Corp. the country Japan as well as was a clearinghouse for any process which was for the improvements. However, we can say that the antitrust concerts forced Research Corporation in 1946 to eliminate territory restrictions.

ESP Working Principle

With the plates which typically spaced about apart we can say that 1 cm to 18 cm depends on the application. The stream which is of air that flows horizontally through the spaces is in between the wires and then passes through the stacks of plates.

A voltage which is negative of several thousand volts is applied between plates and wire. If the voltage applied is high enough an electric discharge of corona ionizes the air around the electrodes which then ionizes the particles in the stream of air.

The particles which are ionized due to the force which is electrostatic are diverted towards the plates and grounded. The build of the particles up on the collection plates and are removed from the stream of air.

What is a Precipitator?

The performance of a precipitator is very sensitive to two particulate properties 1 the  resistivity of the electrical and 2 is the particle size distribution. These properties which can be economically be measured and accurately in the laboratory that are  using standard tests. 

The resistivity that can be determined as a function of temperature which is in accordance with IEEE 548 standard. This test is conducted in an air environment which is containing a specified moisture concentration. The test is run as a function which is of descendants and ascending temperature or both. The Data which is acquired by using an average layer of ash 

The field is of 4 kV/cm. Since the relativity is low which is applied by the voltage used and no vapour that is of sulfuric acid that is present in the environment of the test the values which are obtained by maximum indicate ash resistivity.

In an ESP where there is a charging particle and discharging are known as the key functions of the resistivity and is a very important factor that significantly affects collection efficiency. In this article we already know that resistivity is an important phenomenon in the inter-electrode. The  region where most of the particles which have talked about charging takes place has a particularly very important effect on the layer of dust at the electrode collection where discharging. The particles that exhibit very high resistivity and are difficult to charge. But once these all things are charged they do not readily give up their acquired charge on arrival at the electrode collection. 

On the other hand, we can talk about the particles in the article with very low resistivity that are easily charged and released readily to their charge to the grounded plate collection. Both the extremes impede resistivity the functioning which is efficient for ESPs. the work of ESPs best under normal conditions which is of resistivity.

Hopefully, we have covered all the important points in this article. The form of air or other than that the gases in smokestacks and flues are other. The functions which we have discussed are of precipitator that too by applying the required energy that is only to the particulate matter is being collected without significantly impeding the flow of the gasses. 

Environmental Pollution and Recycling

Environmental pollution has been a major concern for centuries, but it was only during the industrial revolution of the 19th century when it became significant. 

Pollution happens when the environment can’t destroy or degrade an object that causes harm to it.

It is a global challenge where hazardous materials are degraded very slowly by wild animals. The advanced molecular biological tools, when applied to the conventional approach, help us rapidly degrade hazardous materials from the environment.

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Environmental pollution is a desirable change that affects the physical, biological, or chemical characteristics of the components of the environment. 

This causes a harmful effect on the environment.

How is the Environment Polluted?

Environmental pollution is an essential threat to the environment that we are facing today. With each passing year, it is increasing and causing irreparable damage. 

The urbanization of the society, an increasing number of vehicles, factories, household waste, sewage, industrial waste, etc. is increasing day by day, thereby causing environmental pollution.

The discharge of the industrial, domestic, factory, and other waste in the waterways is a major source of pollution. Throwaway of tons of solid and other particulate waste also results in various environmental pollution.

How does Pollution Affect the Environment?

Till now, we have discussed only the causes of pollution. Let us now try to know about the negative effects that are caused to the environment:

a. Effects on Humans

Environmental pollution can cause severe diseases and organ malfunction in humans. These effects can also cause long-term neuro-affections in the body. 

Respiratory problems, skin allergies, asthma, irritation of the eyes, and nasal passages are the common issues that are caused in humans.

b. Effects on Animals

Environmental pollution makes the living environment of animals toxic and inhabitable. Acid rain mainly changes the composition of sea and rivers, making it poisonous for aquatic animals. 

A high quantity of ozone in the lower part of the atmosphere causes serious lung problems for animals.

c. Effects on Plants

Acid rain affects not only animals but also plants and trees. When the plants are affected, it also causes an indirect impact on the animals. 

The growth and development of plant life requires minerals and nutrients, which is unusually destroyed by pollution.

d. Effects on the Ecosystem

Environmental pollution altogether causes damage to the ecosystem by causing a negative impact on it. Most of the environmental pollution is caused by human activities.

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Benefits of Recycling Plastic

There are many benefits of recycling plastic, and we have mentioned here six benefits of recycling plastic:

i. The Great Pacific Garbage Patch (GPGP)

ii. High Economic Impact

Recycling plastic waste generates twice the economic impact compared to just disposing of it in a landfill.

iii. Energy Conservation

The industrial and factory manufacture of any product consists of a number of processes like:

• Extraction of raw materials

• Processing

• Manufacturing

• Removing unwanted waste, and

• Disposal, etc. 

iv. Saving Petroleum

Plastic is usually made from either natural gas or the derivatives of crude oil. Production of plastic requires a large huge array of petroleum products. 

Experiments show that up to 40% of oil consumption can be reduced by recycling plastic waste. According to this figure, recycling a ton of plastic waste can save around 16 barrels of oil.

v. Reduction of CO2 Emission

If the consumption of oil is reduced, it reduces the emission of CO2 and other harmful greenhouse gases. 

The emission of greenhouse gases is also caused by the burning of fossil fuels, which can be reduced to an extent.

vi. Saving Landfill Space

Recycling helps in waste management, as it saves the space available for landfills. 

They require a lot of space as the waste generated is very high and increasing day by day.

Waste Paper Recycling Process

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Recycling of waste paper and its management is one of the most demanded businesses. This is because the paper is the most recycled product in the world.

Paper scrap can be used to produce a new paper product, which in turn benefits the economy significantly.

The recycling process of paper is mentioned below:

a. Collection

The first step of the recycling process is the collection of used paper products. Paper to be recycled is gathered from many different sources and products, and it is kept apart from other types of waste because contaminated papers cannot be recycled.

b. Transportation

After collection, the paper is transferred to a paper recycling plant by an or a truck. The transportation team provides their exceptional service for quick pickup of waste materials. 

c. Sorting

Sorting is a process in which paper is arranged in different categories like cardboard, newspapers, papers, office papers, magazines, etc.

d. Pulping

In the next step, the transported paper is slushed into a pulp and removes large non-fibrous contaminants like staples, plastic, glass, etc.

e. De-Inking

De-inking of paper is done to increase its whiteness and purity. It is done through a combination of mechanical processes that involves shredding and the addition of chemicals.

f. New Paper-Making

This is the final process of paper recycling. A new paper is made in this process. The clean paper pulp is ready to be utilized after this process.

What was Experiment 1 of Faraday and Henry?

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In the first experiment of Faraday and Henry, a coil was connected to a galvanometer. Then a bar magnet was pushed towards the coil This was done in a way that the north pole was pointing towards the coil. It was noticed that as the bar magnet shifted, the galvanometer showcased deflection. The same thing was done with the South Pole.

It was observed in this experiment of Faraday and Henry that the shift and deflection took place only when the magnet was in motion and not when it was stationary. The point of deflection is small or large depending on the speed at which the motion takes place.

The conclusion of the Faraday and Henry experiment was that there was relative motion between the coil and magnet, resulting in the generation of current in the coil.

What was the Second Experiment of Faraday and Henry?

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In this experiment, the bar magnet of the circuit was replaced with another coil that had current generated within it that was connected to a battery. The current coil which was connected to a battery produces a steady current. The second coil that was the primary coil shows deflection in the galvanometer pointer, which indicates the presence of current in it.

Here, same as above, the degree to which the deflection took place depended on the motion of the secondary coil towards the primary coil. The magnitude also depends on the speed with which it was moved. This shows how the second case is analogous to the first.

What was the Third Experiment of Faraday and Henry?

Faraday concluded from the above two experiments that the relative motion between the magnet and the coil resulted in the current generation in the primary coil. However, another experiment by Faraday showed that relative motion between the coils was not necessary for the primary current to be generated. 

He used two stationary coils in this experiment, one connected to the galvanometer and the other to a battery via a push-button. The galvanometer in the other coil deflected as the button was pressed, showing the presence of current in that coil. Furthermore, the deflection in the pointer was only temporary; if the key was pinned down indefinitely, the pointer indicated no deflection, and when the key was released, the deflection reversed.

However, the third experiment of Faraday and Henry showcases that the relative motion is not necessary to produce current. Both of the coils are steadily placed, one is connected to the battery and the other to a galvanometer. The button in the battery when pushed repeatedly does not pass current but when pushed once, the galvanometer deflects.

Hopefully, some concepts of the experiment by Faraday and Henry are clear.

Solved Examples

1. What was not included in experiment 1 of Faraday and Henry?

1. Galvanometer

2. Coils

3. Funnel

4. Battery

Ans: Funnel. There was no funnel in experiment 1 of Faraday and Henry.

2. Find the true statement.

a) The current in the primary did not have to be generated by relative motion between the coils.

b) In the second experiment, the direction of deflection of the pointer is unaffected by the direction of motion of the secondary coil towards or away from the primary coil.

c) The deflections in the galvanometer are the same when the south pole of the bar magnet is moved towards or away from the coil for similar motions as the north pole.

d) When the bar magnet is maintained stationary while the coil is in motion, the effect is different.

Ans: Option d. Is correct. The current in the primary was generated even without relative motion between the coils. In the third experiment, Faraday used two stationary coils and used a push-button to link one to the galvanometer and the other to a battery. The galvanometer in the other coil deflected as the button was pressed, indicating the presence of current in that coil. All the other statements are false.

3. Which of the following factors affects the galvanometer’s deflection?

a) Area of the coil

b) Current passing through the coil

c) Speed with which the bar magnet is dragged toward or away from the coil

d) Resistance offered for current flow

Ans: Option c is correct. The speed with which the bar magnet is dragged towards or away from the coil determines the size of the deflection of the pointer. In addition, the direction of deflection of the pointer is determined by the motion of the bar magnet.

4. Faraday and Henry’s third experiment shows that:

1. Electric current must always be induced by relative motion between the two coils.

2. The relative motion of the two coils is not required to generate an electric current.

3. When the iron rod is placed axially into the coils, the induced current decreases.

4. None of these

Ans: Option b. Is correct. Faraday demonstrated in the third experiment that relative motion is not required to induce a current in the primary coil. When an iron rod is inserted into the coils parallel to their axis, the deflection increases considerably.

5. When a magnet is brought close to a coil: 

(i) speedily 

(ii) slowly

 then induced e.m.f will be:

1. more in (i) case

2. less in (i) case

3. equal in both cases

4. depends on the radius of the ring

Ans: Option a. is correct. When a magnet is rapidly brought near a coil, the number of magnetic fields travelling through the coil changes more speedily, causing the coil to produce more emf.

When a magnet is slowly brought to a coil, the number of magnetic fields travelling through the coil varies slowly, causing the coil to induce less emf. 

6. The primary coil is attached to the galvanometer in Faraday and Henry’s second experiment, while the secondary coil is connected to a battery. When the primary coil is rotated around its axis, then:

1. The current will induce in the primary coil

2. There will be no current generated in the primary coil 

3. The primary coil will create a momentary current.

4. Can’t say.

Ans: Option b. Is correct. According to Faraday and Henry’s second experiment, we can say that when a current-carrying coil is moved closer or away from another coil, an emf is induced in the coil.

• A current will get induced in the coil if the circuit in which the coil is connected is closed.

• To create a current in the coil, relative motion between the two coils is required.

• When the primary coil is rotated around its axis in the given situation, there will be no relative motion between the primary and secondary coils.

• There will be no current in the primary coil since there is no relative motion between the primary and secondary coils.
  

Fun Fact

Faraday has done some praiseworthy work in his years of discoveries. Along with his fellow scientist, Faraday derived words such as electrodes, anodes, and ions for his experiments and was considered futuristic names

Conclusion

This is all about the experiments conducted by Faraday and Henry with a simpler explanation. Focus on how they worked on such experiments and postulated the theories we study today. Study these experiments carefully and understand their outcomes.