Question 1. Explain The Concept Of Density ?
One of the houses feature of each cloth is its density. We look at that a small piece of one cloth may be heavier than a much big piece of every other cloth. The mass per unit extent of a substance is called its density
p = m/V
Units of density are determined by using dividing the chosen unit of mass by using the unit of volume, as kilogram in line with cubic meter, gram per cubic centimeter, or slug consistent with cubic foot.
It is once in a while helpful to use another quantity known as weight-density, or weight in step with unit extent:
D = W/V
Since W = mg,
we've a simple relation among density and weight-density:
D = ρg
Weight-density is generally used while we're involved with consequences depending upon force, at the same time as density is used while mass is to be considered.
Solids and beverages are most effective slightly compresses through even large stresses; hence their densities are almost constant beneath traditional situations. Gases are with ease compressed; therefore it's miles necessary to states the conditions beneath which the densities are measured.
Question 2. Enlighten The Phenomenon Of Electromotive Force ?
In order to preserve an electric current, a few corporation is required to burn up power in shifting the price around a circuit. With the exception of some metals near absolute 0, the superconductors, all conductors gift some competition to the go with the flow of fee in order that paintings have to be performed to preserve a current. An employer capable of causing this type of glide with the aid of converting other varieties of energy to electrical work is known as a seat of electromotive force or a source of modern.
It have to be genuinely understood that a source of modern does no longer manufacture fee however merely moves the price thru a circuit. In most circuits this company is concentrated in a single or a few parts of this employer is concentrated in one or a few pats of the circuit. The source need to create an electric discipline in all parts of the circuit to reason the expenses to move towards the various opposing effects they may come across.
The electromotive pressure, or emf, of a supply is the energy per unit rate converted in a reversible technique. (The time period “electromotive force” is an antique time period now rooted inside the language of physics; its choice turned into unlucky, as this quaintly isn't a pressure. Hence its abbreviation emf can be used hereafter.) In the mks machine, emf can be used hereafter).
An emf causes difference of capacity to exist among factors within the circuit. Thus there may be an intimate relation among emf and capability difference. An emf associated simplest with reversible conversions of strength, whereas ability distinction exists not handiest in source of emf but also in resistors, which convert power to warmness irreversibly. The difference is now and again beneficial and could becomes clearer as we proceed.
In the easy circuit fee drift via the circuit, the cell converts chemical energy to electrical energy, giving upward thrust to an emf. The lamp is a resistive conductor known as a resistor; it converts electric powered power to warmness, and paintings carried out at the charge through the electrical subject, because the fee actions through the resistor, is evidenced with the aid of the presence of a potential difference among the ends of the resistor. A small amount of the whole electric powered electricity transformed from chemical power in the cell additionally produces heat within the cell.
Electric circuits are conventionally reprinted by means of circuit diagrams employing general symbols.
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Question three. Describe Electrostatics In Nature Lightning ?
Man has always been curious approximately and regularly awed with the aid of the strength of lightning> Benjamin Franklin’s test about 2 hundred years in the past with a kite wherein confirmed that lightning consisted of the same sort of electricity that could be produced on the earth by way of electrostatic means is possibly the maximum well-known take a look at fabricated from lightning . Although this phenomenon has been the subject of big studies, scientists have failed to agree upon the cause and the nature of lightning.
We know that lightning is a violent instance of the extremely good electrostatic prices that could occur in nature, however there are numerous extraordinary causes given about the manner wherein the expenses that reason lightning are produced in a cold. Most of these theories are built upon the premise that due to violent air currents in cloud, and the interplay of ions and water droplets and ice [articles, fine terrible costs are produced in a cloud and are then separated with the fine fees moving upward and the poor charges moving downward.
To apprehend this generalization, let us first look at the makeup of a thunderhead clod. In the “mature” level the cloud pinnacle will attain up to ten,000 to 15,000 m (forty,000ft) wherein the temperature is ready -50°C. Within this cloud, which may also have its decrease layer at a height of 5,000 toes and a temperature of around +20°C, there are strong updrafts attaining a pace of 60 mi/h. The water vapor in the cooled under its freezing right now until it has a “seed,” or nucleus, to shape upon, and as a end result it becomes incredible cooled.
However, once ice starts offevolved to form, with crystals develop hastily and fall thru the rising air inflicting a down draft of cold air. When this cold air reaches the lowest of bloodless air. Reaches to the floor simply ahead of the rain, inflicting the once in a while observed chill that rain, causing the on occasion noticed relax that precedes a rainstorm.
Let us keep in mind the maximum famous principle that the lighter “spray like” elements of the torn off darning falling becomes definitely charged and are then carried upward into the cold top layer of the cloud. The heavier debris turn out to be negatively charged and hold to move downward and in so doing acquire more negativity as they grow in size.
Question 4. Describe The Emf Induced By Motion ?
Whenever a change q actions in a magnetic field, the price reports a force F the significance of which given through
F = quB sinθ = q/t lB sinθ
In vector shape the pressure is given by way of
F = qv × B = q/t l × B
The pressure at the charge +q is at right angles to v and B. In the instance illustrated in the force on a tremendous fee might be upward. A shifting price constitutes a modern-day. The force on a rate in movement is that on the equal conventional present day. The vectors representingv, B and F are together perpendicular. If the price is free to respond to this pressure, it will move in the route of F.
An electric powered conductor, consisting of a copper wire, has free electrons in it. Consider a cord moving throughout a magnetic field. The element B sin θ perpendicular to the velocity will exert a pressure on fee within the wire along the route of the wire. Positive prices in the cord could experience a pressure directed towards b; electrons experience a force within the opposite path, and the unfastened electrons collect at a leaving a deficiency of electrons at b.
Equation gives F/q = vB sin θ. Thus an electric subject is set up inside the conductor directed from a closer to b, with a magnitude E = F/q = vB sinθ. The emf e brought on inside the cord of period l is
e = W/q = Fl/q = Eql/q = lvB sin θ
When B is expressed in webers in step with rectangular meter, l in meters, and v in meters in keeping with second, the emf is in joules per coulomb, or volts.
The emf exists whether or not or no longer there may be a entire circuit for modern. If the moving conductor slides alongside stationary accomplishing rails a contemporary could be establishes within the feel proven.
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Question 5. Express Faraday Law Of Electrolysis ?
Quantitative measurements made through Faraday (1833) contributed to the understanding of the procedure going on in electrolytic cells and confirmed a stinking relation between the electrolytic conduct and the chemical houses of diverse substance. Faraday mounted via experiment the subsequent two legal guidelines of electrolysis:
First regulation: The mass of substance separated in electrolysis is proportional to the amount of in electrolysis is proportional to the quantity of strength that passes.
Second law: The mass of substance deposited is electrolysis is proportional to the quantity of energy that passes.
Faraday’s law can be expressed via the subsequent symbolic statements:
m ∝ Q (Q = It)
m ∝ c (c = (atomic mass)/(valence ))
m = kcQ = zQ = zIt (z = kc)
Where k is a proportionality consistent, whose price relies upon handiest upon the gadgets worried, mis the mass deposited, and z is a regular for a given substance (but unique for extraordinary substance), that's called the electrochemical equivalent of the substance underneath attention. The electrochemical equal of a substance is the mass deposited according to unit price. In the mks system it numerically the wide variety of kilograms deposited in one second by way of an unvarying cutting-edge of 1 ampere.
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Question 6. Express The Relation Between Forced Vibration And Resonance ?
Wherever a vibrating frame is coupled to a second frame in this sort of manner that energy may be transferred, the second frame is made to vibrate with a frequency identical to that of the authentic vibrator. Such a vibration is known as a compelled vibration. If the base of vibrating turning fork is set towards a tabletop, the tabletop is compelled to vibrate. This mixture radiates energy faster than the fork may want to on my own. Similarly, a vibrating string is inefficient in transferring electricity to surrounding air unless it's miles coupled to a few sounding board.
Whenever the coupled frame has a herbal frequency of vibration equal to that of the assets, there may be a condition of resonance. Under this situation the vibrator releases extra electricity according to unit time, and the sound is greatly reinforced. Hence the outside energy furnished to a convincing gadget must be accelerated; otherwise its vibrations may be speedy damped.
The reinforcement of sound via resonance with its accompanying release of huge amounts of strength has many useful and plenty of obnoxious outcomes. The resonance of the various obnoxious results. The resonance of the air column in an organ pipe amplifies the otherwise almost inaudible sound of the vibrating airjet. Resonance might produce objectionable distortions of speech or track.
Question 7. How Number Of Lines Of Force Through A Surface Can Be Expressed ?
An advantage of this law is the truth that the net wide variety of lines of force via a floor may be expressed in phrases of the electric subject depth at that surface. An opportunity use of this regulation is the computation of the electric subject depth produced by using symmetrical charge distribution in phrases of the electrical flux produced through those expenses.
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Question 8. Express The Relation Between Number Of Lines Of Force And The Net Positive Charge ?
A signification relation between the internet numbers of traces of pressure passing through any closed surface in the outward direction and the net positive charge enclosed inside that surface become discord charged enclosed inside that floor became found through Karl Friedrich Gauss (1777-1855). In the previous sections it was proven (for the case of an remoted point charge) that the total quantity of lines of electric flux emerging from a charge is exactly identical to that rate (within the mks gadget of units). It is evident that the same internet range of lines of pressure will bypass out of any closed floor of any shape if the floor absolutely encloses the price the generalization of this end is known as Gauss’ law.
The internet variety of strains of pressure in an electric powered discipline that go any closed floor in an outward direction is identical (inside the msk machine) to the internet fantastic price enclosed inside that floor.
In symbols Gauss’ regulation may be stated by using the equation previously given as ψ = ∑Q.
Question nine. Describe Induced Emf And Currents ?
Consider coil of twine linked to a sensitive galvanometer G. If the N pole of a bar magnet is thrust into the coil, the galvanometer will deflect, indicating a temporary modern-day within the coil in the route exact via the arrows. This contemporary in known as an brought about modern and the procedure of producing the emf is called electromagnetic induction. As long because the bar magnet remains at relaxation within the coil, no modern in induced. If, however, the magnet is speedy removed from the coil, the galvanometer will indicated a contemporary inside the direction. Opposite that at emf is prompted whilst there is any change of magnetic flux connected by way of the conductor.
An emf will also be brought about in a coil via the change within the magnetic field related to a alternate in current in a nearby circuit. For example, a coil M related to a battery through transfer S. A 2d coil N connected to a galvanometer is close by. When the transfer S is closed, generating a modern within the coil M inside the path shown, a momentary contemporary is prompted in coil N in a route (arrow a) contrary to that during M. If S is now opened, a momentary cutting-edge will appear in N, having the route of arrow b. In every case there's a cutting-edge in N only while the modern is M is converting. A constant currents in M observed by using a motion of M relative to N is also found to set off a current in N. We found that, in all instances wherein a currents is brought on in N, the magnetic flux through N is likewise changing.
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Question 10. State Lenz Law Of Induced Emf ?
Lenz’s law states that, on every occasion an emf is caused, the triggered present day is in this type of route as to oppose (by means of its magnetic action) the alternate inducing the modern-day.
Lenz’s law is a selected instance of the precept of conservation of power. An prompted contemporary may be produced warmth to do chemical or mechanical work. The work energy ought to come from the work completed to the motion of a magnet or a coil, paintings is completed; consequently the motion ought to be resisted by means of a force. This opposing force comes from the action of the magnetic area of the caused modern. When a trade in current in a number one coil induces an emf in a neighboring secondary coil, the present day in the secondary may be in such a route as to require the expenditure of additional strength inside the primary to keep the modern.
Question 11. Describe The Various Systems Of Units In Electrostatics ?
Two families of units are useful in the regions of electrostatics: the mks machine and the gadget of cgs electrostatic units (esu). The electrostatic units will first be considered because of their historical significance and their simplicity.
If may be visible that there are new ideas to be defined which have no longer formerly been considered, specifically, the ones represented by the electrostatic gadget to selected the concept represented through the symbols ok and Q. It's far most convenient inside the electrostatic device to selected the idea represented by using k as the one to be arbitrarily specified as essential (like length, mass, and time in mechanics). Then Q can be described from Coulomb’s law. From this settlement, k is arbitrarily assigned the cost of exactly. I dyn cm2 in line with unit charge2 for empty space. The esu of charge, generally called the statcoulomb (statiC), is defined as a factor charge of this kind of importance that it's miles repelled by using a force of one dyne if it is placed one centimeter faraway from an same charge in empty space. The size of the statcoulomb makes it convenient for many troubles in electrostatics.
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Question 12. Determine The Construction Of Ac Generator ?
The simplest viable generator is a single coil of wire rotating in a uniform magnetic subject. The emf caused in this type of case is an alternating emf, and for this reason this kind of generator is known as and therefore the sort of generator is called an ac generator. The coil wherein the emf is triggered is called the armature.
A high voltage may be received in an ac generator through having the coil wound on an iron middle, the flux connected by means of the coil being as a consequence increased, and also by means of having a large variety of turns in series for every coil. Where the coil rotates, the ends of the coils are related to round ring referred to as accumulating rings or slip jewelry. Carbon (graphite) brushes pertaining to these rings make connection to the outside circuit. The primary elements of an ac generator are (1) a area magnet, (2) the armature genitors the armature is made desk bound and the field magnet is triggered to rotate.
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Question 13. State Faraday Ice Pail Experiments ?
Several big experiments, at the beginning done by way of Faraday with a metallic ice pail and an electroscope, are useful in illustrating a number of the information stated above. The pail is connected to the electroscope with the aid of a engaging in wire.
When a charged ball, held by an insulating thread, is decreased into the pail, the leaves of the electroscope diverge, displaying that they own an precipitated price. No rate within the divergence of the leaves is observed while the charged ball is moved to various locations in the pail. This proven that the variety of brought on prices in the pail is simply equal to the price on the ball. Now, if the ball is touched to a wall of the pail, no rate inside the divergence of the leaves is determined. The ball is found to have misplaced its price and the outside of the pail and the electroscope has won the fee lost by means of the ball. When the ball touches the wall, its fee simply neutralizes the charges of contrary sign that had been on the interior of the pail.
If the ball is once more similarly charged and reintroduced into the pail and touched to the pail, it will be located that the pail acquires an additional charge, same in significance and signal to the unique price. This manner may be persisted until the pail is charged to a completely excessive capability.
Question 14. Consider The Thermoelectric Effects Of Current ?
In considering thermoelectric effects, we have to recognise that we are coping with a non-equilibrium situation. A standard concept of non-equilibrium is beyond our approach, suffice it to mention that Lars Onsager, with a paper entitled” reciprocal family members in irreversible processes” caused a few fundamental insights as overdue as 1930; he obtained the Nobel Prize for his contribution to non-equilibrium thermodynamics in 1968-for chemistry, of all matters. However, what we need to aware about, is the vital assertion of non-equilibrium principle:
As lengthy as there is no equilibrium, we always have currents of some thing looking to set up equilibrium with the aid of reducing a gradient in something else this is the real cause of the non-equilibrium. A gradient in the electrical capacity, e.G., cause out famous electric currents, and a gradient in a attention reasons diffusion currents.
But we ought to abstract even greater, and keep in mind such things as entropy currents in addition to all types of combos of gradients and currents
While Onsager located some pretty wellknown members of the family among gradients and currents, we will no longer delve into details right here, however most effective look a bit greater carefully at what reasons a few thermoelectric outcomes of contemporary.
Question 15. Describe Seebeck Thermoelectric Effect Of Current ?
See beck in 1821 found that if wires of different metals say copper and iron are joined at their ends A and B thru a low resistance galvanometer G to from a closed circuit and if one of the junctions say A is heated and the alternative junction B is saved bloodless the galvanometer shows a deflection this must be because of a cutting-edge within the circuit called thermo eclectic modern-day the modern-day need to in addition be due to certain referred to as thermo the assembly of two distinctive metals joined at their ends to have two junctions in a circuit is referred to as a thermocouple. This phenomenon of thermo-power changed into discovered first of all with the aid of see beck. Hence it is also known as see beck impact.
Thus see beck effect is the phenomenon of era of an electric powered current in a thermocouple with the aid of maintaining its two junctions at exclusive temperatures.
The route of modern-day in Cu – Fe thermocouple is from Cu to Fe through warm junction and can be remembered by way of the world chl. In Sb-Bi thermocouple the path of contemporary is Sb to Bi through cold junction it is able to be recollected by way of ABC.
See beck observed that the importance and path of thermo developed in a thermo couple depends up.
The nature of metals forming the thermo couple.
Difference in temperatures of the 2 junctions.
The see beck impact is reversible. It means if the hot and the bloodless junctions are interchanged. The route of thermoelectric present day is reversed. Thus see beck impact is a reversible effect.
See beck from his experimental investigations organized some of metals in a series realize as see beck collection. Some of the metals of this collection inside the order see beck organized them are given below.
Bi, Ni, Co Pd, Pt, Cu, Mn, Hg, Pb, Sn, Au, Ag, Zn, Cd, Fe, Sb, Te,.
When any two of these metals from a thermocouple current flows thru the hot junction from a metal occurring earlier, to a metallic happening later, within the series.
See beck also determined that for a given distinction of temperatures of junctions the larger is the distance in see beck series between the metals forming the thermo couple the greater could be the thermo emf. Generated. That is why thermo emf evolved is most in a thermo couple of antimony and bismuth for a given difference in temperatures of the two junctions. The thermo emf is of the order of 10-3 V or less.
For a temperature distinction of 100C between the two junctions the thermo produced in Cu-Fe. Thermocouple is best zero.0013V and in Sb-Bi thermocouple is zero.008V.
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Question sixteen. Describe The Origin Of Thermo ?
When different metals are brought into contact, at the junction the loose electrons have a tendency to diffuse from the steel swath extra free electron density to the opposite with lower loose electron density due to this diffusions a capacity different is advanced at the junction of the 2 metals known as touch capacity when booth the junctions are at the same temperature the touch potentials at the 2 junctions will be the equal.
Hence no modern-day flows inside the thermocouple. But if one junction identification heated up the rate of diffusion of loose electrons at that junction will fee. As a end result of it’s the contact potentials at the 2 junctions becomes distinctive and there might be an powerful ability distinction in the circuit known as thermo.
Thus the time period produced in a thermocouple is identical to the difference in contact potentials at the two junctions A and B and is given by using V AB = V A – V B
Question 17. Describe The Construction And Working Of Thermoelectric Thermometers ?
A thermoelectric thermometer is used for the measurement of temperatures each low and high.
Principle: Its working is primarily based on see beck effect thermocouples of different metals are constructed relying upon the temperature to be measured.
Construction: The wires forming the thermocouple are welded collectively at one stop and this stop bureaucracy the new junction. The quantities of the wires near the recent junction are nicely insulated from every different by enclosing them in a difficult-glass capillary tube C.T. The wires are surpassed via mice discs D, which might be outfitted one above the other in a porcelain tube T. The ends of these wires are connected to the terminals T1 and T2 to these terminals are linked compensating leads L1 and L2 of the equal materials as those forming the thermocouple itself. By so doing the cold junction is shifted to a convenient place in which a constant temperature of OC is maintained.
By maintaining hot junction at one of a kind recognized temperatures the corresponding values of thermo are cited using distal voltmeter within the circuit of thermocouple. The digital voltmeter gives its inner resistance is very high (approximately 10 ?). A graph plotted among the temperature of warm junction and Themo the curve so acquired is known as calibration curve.
To find the unknown temperature of a given tub the recent junction is placed inside the given bathtub. The thermo so generated is measured. The temperature corresponding to this value of thermo is determined from the calibrations curve.
Note it's far important to notice that thermocouple have to not be used to degree the temperature above the neutral temperature.
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Question 18. Describe The Advantages Of Thermoelectric Thermometers ?
Thermoelectric thermometers may be used over plenty wide3er variety of temperatures; starting from – 200C to 1600C.
These thermometers are cheap and can be built easily.
These can be used to measure the temperature of small cavity.
Their thermal ability being low they reap the temperature to be measured very quickly and are therefore beneficial for measuring changing temperatures.
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Question 19. What Are The Disadvantages Of Thermoelectric Thermometers ?
Since these thermometers are not direct riding thermometers in order that they can't be used for calorimetric purposes.
There is not any common relation connecting thermo and the temperature of a junction in any thermocouple. Therefore the given thermo couple must be calibrated first.
For the dimension of temperature over distinctive stages, exclusive thermocouples are to be used.
Question 20. Define Thermoelectric Power ?
Thermo electric powered energy is described as the rater of price of thermo with temperature it's also referred to as see beck coefficient and is denoted via S.
From experimental look at it was concluded that the variant of thermo e with the temperature C of the recent junction when cold junction is at OC is a parabolic curve represented via the equation
E = a θ + 1 / 2 β θ2
Where a and β are constants which depend upon the character of the metals forming the thermocouple and the temperature difference of the 2 junction.
The thermoelectric power (known as see beck coefficient) is given via
S = dE/d θ = ∝ + β θ
It manner S ∝ θ
Question 21. Describe The Construction Of A Thermopile ?
A thermopile is a touchy tool used for detection of warmth radiation and measurement in their intensity. It is based totally upon see beck effect.
A thermopile includes a number of thermocouples of Sb –Bi all linked in series. One set of junctions on one facet is coated with lamp black. The other set of junctions on the other side is properly polished. The arrangement is enclosed in a funnel or horn shaped vassal. The two ends T1 and T2 of the thermopile are related to a touchy galvanometer.
Heat radiations coming from the funnel shaped side of the vessel are made to fall on the set of junctions lined with lampblack. These are absorbed and consequently the temperature of all the junctions on this set is raised. The different set of junctions being polished mirror those radiations and remain cold. Thermo is developed in every thermocouple. As thermocouples are linked in series, the thermoelectric present day in every drift is inside the identical junction. The overall cutting-edge is consequently large and produces deflection in the galvanometer.
The deflection within the galvanometer suggests the existences of warmth radiations. The deflection is calibrated to degree directly the intensity of warmth radiations. This instrument is so touchy that it may discover warmness radiations from match stick lighted at a distance of fifty meters from the thermopile.
Question 22. Describe The Working Of A Thermoelectric Refrigerator ?
The operating of thermo-electric refrigerator is based totally on pettier impact. According to pettier impact, if contemporary is passed thru a thermocouple warmth is absorbed at one junction and developed at the other junction of the thermocouple. If at the entire the heat is a boarded, the thermocouple acts as thermoelectric refrigerator. Such a refrigerator has no muter or compressor. Its correctly is small in assessment to congenital fridge. Thermo electric powered refrigerator could be very beneficial when the vicinity to be cooled is very small and the noise is not perfect.
The thermocouple decided on for using thermoelectric fridge should have the subsequent characteristics.
Low resistivity so that the lack of electricity within the form of joule warmth is minimum.
Low thermal conductivity it's going to help in keeping big temperature difference among the 2 junctions.
High thermo electric electricity.
Question 23. What Is A Thermoelectric Generator ?
Thermocouple may be used to generate electric powered power using are looking for beck impact in remote regions. It may be executed by means of heating one junction in a flame of kerosene oil lamp and retaining the alternative junction at room or atmospheric temperature. The thermo so developed is used to perform radio receivers or even radio transmitters.
Question 24. Describe Thomson Effect Of Evolution Of Heat ?
Thomson’s effect changed into discovered by Thomson (later referred to as Kelvin). According to this effect, if two elements of a single conductor are maintained at special temperatures, an e.M.F. Is evolved among them. The e.M.F. So produced is called Thomson’s e.M.F. If the constant modern is exceeded thru an unequally heated conductor, an absorption or evolution of heat in excess of Joule’s heat, takes location in the conductor.
Thus Thomson’s impact is the absorption or evolution of heat in extra of Joule heat whilst modern is surpassed thru an unequally heated conductor. Thomson effect is reversible effect.
To recognize Thomson’s effect, recall an unequally heated rod AB of copper. Let the give up A of the be at higher temperature than its end B. On passing the current from A to B within the rod, warmness is developed alongside the period of the rod. In case, the contemporary is surpassed inside the rod from give up B to A, the heat is absorbed along the duration of the rod. It is accounted because of the fact that during case of copper, the hot end of the rod is at better capability and its cold end is at decrease potential.
When modern flows from warm stop to cold give up of copper rod i.E. From better ability to lower ability, the power is produced that's radiated out inside the shape of heat. When modern-day is flowing from bloodless quit to hot give up of the copper rod i.E. From lower potential to better capability, the electricity required which debts for the absorption of heat energy. Thomson’s impact for copper is wonderful. Other substances showing fantastic Thomson’s impact are Sb, Ag, Zn and so on.
There are a few other materials like Fe, Co, Bi, Pt etc. For which Thomson’s impact is negative. It way for such metals, Thomson’s impact is simply reverse as that for copper. It way, in step with Thomson’s impact for iron rod, warmth is absorbed when present day is passed from warm give up to bloodless stop and warmth is evolved while modern-day is exceeded from cold stop to warm end of the rod.
For lead, Thomson’s effect is nil. It means no warmth is evolved or absorbed while modern is passed via an unequally heated rod of lead. It is due this cause that lead is used as a reference metal in thermoelectricity.
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Question 25. Explain Area Vector ?
Area is a scalar quantity. But in some of the issues it's far convenient to treat it a a vector. The query is a way to companion a vector to the area of a curved surface. Let us divide the given closed location right into a big wide variety of very small place elements. Each small area detail can be handled as planar. As everyday to the plane specifies the orientation of the area, therefore, the path of a planar region vector is alongside its everyday. But a ordinary can point in guidelines, inwards or outwards. By conference the vector associated with every vicinity detail of a closed floor is taken to be within the route of the outward normal.
Thus, a place detail vector S at a point on a closed floor can be written as
Δ = (Δ )
wherein S in importance of the area element and is a unit vector inside the path of outward everyday at that factor.
Question 26. How Does Electric Flux Represent The Field Lines ?
Electric flux over an area in an electric powered area represents the whole quantity of subject lines crossing this region.
We know that the quantity of subject lines crossing a unit area positioned everyday to the sector at a factor is a degree of energy of electric subject E at that factor. If we location a small planar element of place ?S everyday to E at this factor, number of electric filed strains crossing this area detail is proportional to E (?S) be aware that it isn't proper to mention that variety of subject strains crossing the place is equal to E (?S). The wide variety of discipline strains is in the end a count of how many field traces we choose to attract. What is physically sizeable is the relative range of field strains crossing a given place at distinctive points.
If we tilt the area detail by using angle θ [or we tilt E w. Region element through perspective θ, the range of subject lines crossing the area can be smaller. As projection of location detail normal to E is ?S cos θ (or element of E normal of electrical filed traces crossing area ?S is proportional to E?S cos θ.
Question 27. Describe The Relation Between Electric Intensity And Electric Potential ?
To attain relation among electric powered intensity E and electric capacity V, allow us to consider equipotential surfaces A and B spaced intently as shown in fig. 1 (c) allow the ability of A be VA = V and potential of B be VB = (V + dV) where dV is increase in potential inside the route of electric intensity E everyday to A and B.
Suppose dr is perpendicular distance between the two equipotential surfaces. When a unit positive rate is taken along this perpendicular distance from the surface B to the surface A in opposition to the electric area.
Work accomplished dr
WBA = VA – VB = V – (V + dV) = - dV
capability power of a mass in a gravitational field we are able to outline electrostatic ability energy of a charge in an electrostatic field.
For the sake of simplicity, allow us to expect that electrostatic field is due to price + Q positioned on the foundation. Let a small take a look at rate + q be delivered from a point A to some extent B, against the repulsive pressure on it because of price + Q we will count on that the check rate +q is so small that it does no longer disturb the original configuration of charge + q on the origin similarly we anticipate that an external force ext applied is simply enough to counter the repulsive electric powered force at the test fee q in order that internet pressure on take a look at fee q is zero and it maces from A to B with none acceleration.
In this example, paintings performed by means of external pressure is evasive of labor achieved by way of the electrical pressure and gets absolutely saved within the rate q inside the shape of its potential power.
On attaining B, if the external force applied on q were eliminated, the electrical pressure will take the take a look at charge + q faraway from source charge + Q. The strode potential strength at B is used to provide kinetic electricity to the charge q in one of these way that the sum of kinetic and potential energies at each factor is conserved.
Question 29. What Does Electrostatic Potential Of A Body Represents?
Basically electrostatic capability of a frame represents the diploma of electrification of the frame it determines the direction o go with the flow of charge between charged bodies positioned in touch with each other. The price usually flows from a frame at better potential to some other frame at decrease potential the float of rate stops as soon as the potentials of the 2 bodies emerge as identical.