# CURRENT ELECTRICITY

Unit 14

Q.1. What is outline and justify the term current?

Ans. The rate of flow of electrical charge, through any cross-sectional space is named current.

If the charge letter is passing through any cross-sectional space in time t, then current I flowing through it’ll tend by

Charge Current B-T I Sie

.or I = -t-

Unit: The SI unit of current is ampere (A).

Q.2. What does one mean by typical current? justify.

Ans. typical CURRENT

The current flowing from positive to negative terminal of A battery because of the flow of positive charges is named typical current.

In a argentiferous conductor, current is often because of the flow of free electrons. however we tend to suppose that very same quantity of charge additionally flows within the wrong way. As current is measured by the impact that it produces, therefore, we will say that a current made because of the flow of negative charges is corresponding to the flow of associate degree equal quantity of charge. This equivalent flow of positive charges is understood as “conventional current”. Thus, we tend to assume that current is often because of the flow of charge.

Q.3. what’s distinction between electronic current and traditional current?

Ans. Electronic current flows because of the motion of electrons (negative charges) from the negative terminal of the battery to the positive terminal. Whereas typical current flows because of the motion of positive charges from the positive terminal of the battery to the negative terminal.

Q.4. what’s meter and ammeter?

Ans. meter

A meter is extremely sensitive instrument and might sight little current during a circuit.

A current of few million peres is adequate to cause full scale deflection during a meter. a perfect meter ought to have terribly little resistance to pass the most current within the circuit. A meter is often connected serial.

AMMETER

An ammeter, could be a current measuring device.

A large current of the vary like 1A or 10A are often measured by suggests that of associate degree meter. associate degree meter is connected serial, therefore the current flowing within the circuit additionally passes through the meter.

Q.5. what’s meant by potential drop and emf (emf)?

Ans. potential drop

The work that should be done between any 2 purposes against electrical forces to maneuver a unit charge kind one point to the opposite is named potential drop.

ELECTROMOTIVE FORCE (e.m.f.)

Electromotive force is that the total quantity of energy provided by the battery in moving one coulomb of charge from the negative to the positive terminal of the battery. .

Energy therefore electrical phenomenon =C Rirge-

W or “Q wherever E is e.m.f, W is energy and letter is charge.

Q.6. Is e.m.f. extremely a force? justify.

Ans. emf (e.m.f.) is truly a voltage between the terminals of the battery, once no current flows within the circuit. it’s constant units as that of the voltage. Thus, it’s not extremely a force.

Q.7. however will we tend to differentiate between e.m.f. and potential difference? during which units these square measure measured?

Ans. The emf (emf) of A battery or a cell is that the total energy provided in driving one coulomb of charge spherical an entire circuit during which the cell is connected. the entire circuit includes the cell itself associate degreed an external circuit connected to the terminals. Whereas the potential drop determines the energy needed between any 2 points of the circuit, in moving a charge from one purpose to a different.

Unit: The e.m.f. and potential drop each square measure measured in volts.

Q.8. however will we tend to live current during a circuit?

Ans. whereas mensuration the present during a circuit, the polarity of the terminals of the meter and also the meter ought to be taken into consideration. Generally, the terminal with-red color shows the positive polarity and also the terminal with black color shows the negative polarity. each meter and meter square measure connected serial.

Q.9. what’s voltmeter? however potential drop across a circuit are often measured?

Ans. VOLTMETER

An instrument wont to live potential drop across a circuit is understood as meter.

In order to live voltage or potential drop, the positive terminal of the battery is connected to the positive terminal of the meter and also the negative terminal of the battery is connected to the negative terminal of the meter. A meter is often connected in parallel with the device across that the potential drop is to be measured.

Q.10. however will we tend to live e.m.f. of the battery?

Ans. activity OF e.m.f.

In general, e.m.f. suggests that the potential drop across the terminals of the battery once it’s not driving current within the external circuit. thus so as to live e.m.f. of the battery, we tend to connect the meter directly with the terminals of the battery.

Q.11. State and justify law. What square measure its limitations?

Ans. OHM’S LAW

It states that:

The amount of current I passing through a conductor is directly proportional to the potential drop V applied across its ends, provided the temperature and also the physical state of the conductor doesn’t amendment.

i.e. Varl

or V= IR / wherever R is that the constant of quotient, and is that the resistance of the conductor. If a graph is aforethought between the present I and also the potential drop V, a line are obtained.

Resistance

The property of a substance that offers opposition to the flow of- current through it’s referred to as its resistance.

Unit: The Si unit of resistance is ohm (Q).

When a possible distinction of 1 potential unit is applied across the ends of a conductor and one ampere of current passes through it, then its resistance are one ohm.

Limitations of law

Ohm’s law has the subsequent limitations:

1.Ohm’s saw m applicable solely in conductor, once their temperature and physical state doesn’t amendment.

2.It is applicable solely in argentiferous conductors.

Q.12. however will we tend to differentiate between resistance unit and non-ohmic conductors?

Ans. Such materials that adjust law, and thence have a relentless resistance over a good vary of voltages, square measure same to be resistance unit conductors. Whereas the materials having resistance that changes with voltage or current square measure carried resistance unit conductors.

Q.13. What square measure the characteristics of resistance unit and non-ohmic conductors?

Ans. CHARACTERISTICS OF resistance unit CONDUCTORS

Ohmic conductors have a linear current-voltage relationship over an oversized vary of applied voltages The line shows a relentless quantitative relation between voltage and current. law is obeyed by the resistance unit conductors. for instance, most metals show resistance unit behaviour.

CHARACTERISTICS OF NON-OHMIC CONDUCTORS

Non resistance unit materials have a non -linear current-voltage relationship. for instance, filament lamp, and thermister square measure non-ohmic materials. The resistance of filament rises (current decreases) because it gets hotter, that is shown by the gradient obtaining vessel.

Q.14. what’s a thermister.

Ans. THERMISTER

A resistance circuit part whose resistance decreases as temperature will increase in referred to as a thermister.

A thermister could be a temperature dependent resistance and its resistance decreases as temperature rises. A thermister is employed during a circuit that senses natural action.

The resistance of a thermister decreases (current increases) because it gets hotter. this is often as a result of on heating, a lot of free electrons become out there for the conductivity of current.

Q.15. Why will the resistance of a conductor will increase with the increase of its temperature?

Ans. typically a argentiferous conductor includes a crystalline structure during which its numerous atoms within the variety of positive ions square measure fastened at their several places. Free electrons move within the areas between these atoms. once the present follows through the conductor, the opposition to the flow of current is caused by the collision of free electrons w ;h the atoms of the conductor. a lot of oftentimes electrons run into the atoms; the larger is that the opposition or resistance within the flow of current.

When the temperature of the conductor rises, average speed of the random motion of the free electrons will increase, that enhance the speed of collisions of electrons and also the atoms. This causes a rise within the resistance of the conductor.

Q.16 What square measure the factors upon that the resistance of a conductor depends?

Ans. The resistance of a conductor depends upon the subsequent 3 factors:

Length
The resistance R of a wire is directly proportional to the length L of the conductor. Mathematically

It is written as RocL

Cross-sectional space
The resistance of a wire is reciprocally proportional to the world of crosswise of the wire. Mathematically,

Roc A

Temperature
The resistance of a.wire is directly proportional to the temperature of the conductor. Mathematically,

Roc T

Q.17. what’s meant by specific resistance or Resistivity?

Ans. As resistance is directly proportional to the length of the conductor and reciprocally proportional to the world of crosswise of the conductor, which may be

written as

i Roc L …… 1

and I

By combining these 2 equations, we get

L or R = pT- …… (iii)

where p is that the constant of quotient, referred to as specific resistance. Its price depends upon the character of the conductor. for instance, copper, iron, tin, and silver would every have a unique values of p.

If we tend to place L = 1m, and A = 1m2 in combining weight. (iii), then R = p, i.e. specific resistance or impedance in outlined as:

The resistance of 1 metre cube of a substance is adequate its specific resistance or impedance.

Unit: The SI unit of specific resistance is ohm-meter (Qm)

Q.18. what’s the distinction between conductors and insulators?

Ans. CONDUCTORS

The materials which permit electricity to undergo them square measure referred to as conductors.

Conductors have far more than free electrons that don’t seem to be command powerfully with any explicit atom of the metals. These free electrons move willy-nilly altogether directions within metals. after we apply external force field, these electrons will simply move during a specific direction. This movement of free electrons {in a|during a|in associate degree exceedingly|in a very} explicit direction underneath the influence of an external force field causes the flow of current in

the metal wire.

INSULATORS

The materials that don’t enable electricity to undergo them square measure referred to as

insulators.

All metals, like; silver and copper square measure conductors.

The electrons in insulators, like rubber, don’t seem to be liberal to move. they’re tightly certain within true atoms. Hence, current cannot flow through associate degree material as a result of there are not any free electrons for the flow of current. Insulators have terribly massive price of resistance. Insulators are often simply charged by friction and also the iatrogenic charge remains static on their surface. different samples of insulators square measure glass, wood, plastic, fur, silk, etc.

Q.19. however square measure resistors connected in series? confirm the equivalent resistance of series combination of resistors.

Ans. RESISTORS CONNECTED serial

In series combination, resistors square measure connected finish to finish and current includes a single path to flow through the circuit. This, implies that the present ‘passing through every resistance is that the same.

The total voltage during a circuit divides among the individual resistors therefore the total of the voltage combination

across the resistance of every individual resistance is equal

to the toiai voltage provided by the supply (battery). Thus, we will write as

V = V1+V2 + V3 …… (i)

where V is that the voltage across the battery, and V^ V2, V3 square measure the voltages across resistors R1, R2 and R3 severally. If I is that the current passing through every resistance, then, Eq.(1) are often written as:

V = IR1 +IR0-HR3

(2) we will replace the mix of resistances with one resistor referred to as the equivalent resistance Re such constant current passes through the

circuit.

From law

V = IRe therefore combining weight. (2) becomes

IRe = I(R, + R2

R3)

(3)

Thus the equivalent resistance of a series combination is adequate the total of the individual resistances of the mix.

If resistances R1t R2, R3, …, Rn square measure connected serial, then the equivalent resistance of the mix are given by

Re = R1 + R2 + R3-H…+Rn ‘

Q.20. Write down the characteristics of series combination of resistors.

Ans. CHARACTERISTICS OF SERIES COMBINATION OF RESISTORS

In this combination, the magnitude of current that flows through every individual resistors is that the same.
The total of voltages across every of the resistance is adequate the voltage of the battery connected across the mix.
3.. i.e. V = V, + V, + V,

The equivalent resistance of a series combination is adequate the total of the individual resistances of the mix. i.e. Re = r! + R2

Q.21. however square measure resistors connected in parallel? confirm equivalent resistance of the parallel combination of resistors.

Ans. PARALLEL COMBINATION OF RESISTORS rf—

In (.Parallel combination, one finish of every resistances W-I g connected with positive terminal of the battery whereas the opposite finish of every resistor is connected with the

negative terminal of the battery. Therefore, the voltage is same across every resistance that is adequate the voltage of battery. parallel combination

i.e. V = V1 = V2 = V3

In the loop, the whole current is adequate the total of the currents within the numerous resistances.

i.e. I^+12 + Lj …… (1)

Since the voltage across every resistance is V, thus by law V.

Thus Eq. (1) becomes

V V V

We can replace the mix of resistances with one resistor referred to as the equivalent resistance Re such constant current passes through the circuit. From

Ohm’s law:

= V/Re

Thus, Equation (2) becomes r~d d

R Thus, the equivalent resistance of a parallel combination is total of the reciprocal of the individual resistances, that is a smaller amount than any of the individual resistance connected within the combination. If resistances R.,, R2, R3, Rn square measure connected in parallel, then the equivalent resistance of the mix are given by L•

Q.22. Describe the characteristic options of parallel combination of resistors. Ans. CHARACTERISTICS OF PARALLEL COMBINATION OF RESISTORS

1.In this combination, the voltage across all the resistances is same.

2.The total of the currents flowing through the varied resistances of this mixture is adequate the whole current of the circuit. .

i.e. I = I., + I2 + I3

If resistance R v R2 and R3 square measure connected in parallel, then their equivalent resistance are often determined by victimization the formula:
Q.23. What square measure the benefits of parallel circuits over series circuits?

Ans. Parallel circuits have 2 huge benefits over series circuits.

1 . during a loop, every device receives the total battery voltage.

In a loop, every device is also turned off severally no end the present flowing to the opposite device within the circuit. This principle is employed in house wiring.
Q.24. State and justify Joule’s law.

Ans. JOULE’S LAW

The amount of energy generated during a resistance because of the flow of charges is adequate the merchandise of sq. of current, resistance and also the time period.

Consider 2 points with a possible distinction of V volts. If one coulomb of charge passes between the.se points; the number of energy delivered by the charge would be V joules. Hence, once letter coulomb of charge flows between these 2 points, then we are going to get QV joules of energy. If we tend to represent this energy by W, then

Electrical energy provided by letter charge W = QV joules

Now current, once charges letter flow in time t, is outlined as

1=^ t

or letter = It thus

Energy provided by letter charges W = V x I x t

This voltage are often regenerate into heat and different forms within the circuit.

From law, we have

V = IR therefore

V2t Energy provided by letter charges W = I2 R t = ~p-

This equation is named Joule’s law.

Q.25. however is energy dissipated during a resistance? justify.

Ans. The voltage are often used for various helpful functions. for instance, bulb converts voltage into lightweight and warmth, heater and iron convert voltage into heat, and fans into energy. Usually, this energy seems as heat within the resistance. this is often the rationale that we tend to get heat once current passes through a heater.

Q.26. What does one mean by electrical power? outline its unit

Ans. electrical power

The amount of energy provided by current in unit time is understood as .electric power.

Electric power are often determined by the formula:

Electrical Energy electrical power = — T|me——

Or p wherever W is that the voltage given by

W » QV. Therefore, power P are often written as

 Appliance Power (watts) Electric stove 5,000 Electric heater 1,500 Hair dryer 1,000 Iron 800 Washing machine 750 light 100 Small fan 50 Clock radio 10

Unit: The SI unit of power is watt (W).

Watt

If- one joule of energy is supplied for one second, then electric power will be one watt.

i.e. 1W = 1 Js~1

Q.27. what’s kilowatt-hour? however energy in kilowatt-hour may be obtained?

Ans. KILOWATT-HOUR

The amount of energy delivered by an influence of 1 kW m one hour is named kilowatt-hour.

One kilowatt-hour (1 kWh) = lOOOWxl hour

= one 000 Wx (3600s) \ kWh =36x 105J = three.6MJ The energy in kilowatt-hour may be obtained by the subsequent formula:

watt x time(in hours) the number of energy in kilowatt-hour = – ——— 10QQ ——

Q.28. however will the value of electricity consumed in an exceedingly house be calculated?

Ans. the electrical meter put in in our homes measures the consumption of electrical energy within the units of kilowatt-hour consistent with that we have a tendency to pay our electricity bills. If the value of 1 kilowatt-hour i.e. one unit is understood, we are able to calculate the number of electricity bill by the subsequent formula:

Cost of electricity = variety of units consumed x price of 1 unit nine watt x time(in hours)

1000

x price of 1 unit

Q.29. Define d.c. and a.c.

Ans. electrical energy (d.c.)

A current that flows solely in one direction is named electrical energy.

ALTERNATING CURRENT (a.c.)

A current that changes its direction once more and once more is named alternating

current.

Q.30. what’s distinction between d.c. and a.c.?

Ans. this derived from a cell or battery is electrical energy (d.c.), since it’s one-way. The positive and negative terminals of d.c. sources have mounted polarity, thus level of d.c. remains constant with time. On the contrary, there’s conjointly a current that changes its polarity once more *and once more. Such a current is named AC or a.c.

Q.31. outline the term fundamental measure and frequency.

Ans. fundamental measure

The quantity when that the a.c. voltage or current repeats its price is understood as fundamental measure.

FREQUENCY

The number of cycles that this completes in one second is named its frequency.

The relation between frequency and fundamental measure is

This shows that frequency is that the reciprocal of your time amount.

Q.32. The voltage chosen for the transmission of wattage over giant distances is again and again bigger than the voltage of the domestic provide. State 2 reasons why wattage is transmitted at high voltage.

Ans. the explanations for transmission of -high voltage ar as under:

Sending power at high voltage would cut back the facility loss within the type of chilling i.e. I2Rt. For same power, high voltage means that lower current and thence less power loss.
For same power, causing power at high voltage means that low current. It means that • we want dilutant wires and conjointly less variety of repeater increase transformers to send power over long destinations.
Q.33. Why is that the voltage used for domestic provide a lot of not up to the voltage at that the facility is transmitted?

Ans. Domestic appliances care for low voltage. Therefore, high voltage will injury these instruments. Also, high voltage may be dangerous for users because it will cause electrical shock. it should conjointly injury property and alternative valuables as a results of some serious electrical shock.

Q.34. Describe in short the hazards of home electricity.

Ans. Major hazards or dangers of electricality ar electric shock and hearth. Here we have a tendency to discuss some faults in electrical circuits which will cause electricity hazards.

INSULATION injury

All electrical wires ar well insulated with some plastic protect the aim of safety. however once electrical current exceeds the rated current carrying capability of the conductor, it will manufacture excess current which will injury insulation thanks to heating of cables. This results into a brief circuit which may severely injury electrical devices or persons.

DAMP CONDITIONS

Dry human skin has resistance of a hundred,000 ohms or more! however beneath damp conditions, resistance of human skin is reduced drastically to few hundred ohms. Therefore, ne’er operate any electrical appliance with wet hands. conjointly keep switches, plugs sockets and wires dry.

Q.35 however will contact occur and the way will it’s avoided?< .

Ans. a brief circuit happens once a circuit with a really low resistance is made. The low resistance causes this to be terribly giant. once applicances ar connected in parallel, every further appliance placed in circuit reduces the equivalent resistance within the circuit and will increase this through the wires. this extra current would possibly manufacture enough thermal energy to soften the wiring’s insulation, inflicting a brief circuit.

Short circuit may occur once the livewire and therefore the neutral wires are available direct contact.

In order to avoid true of contact, the wires carrying electricity ought to ne’er be naked. Rather it ought to be coated with a decent stuff.

Q.36. Describe some safety measures that ought to be in reference to the home circuit.

Ans. so as to safeguard persons, devices and property from the hazards of electricity, the subsequent measures ought to be taken in home electricity:

FUSE
A fuse may be a guard that’s connected asynchronous with the actor within the circuit to safeguard the instrumentality once excess current flows. it’s short and skinny piece of metal wire that melts once giant current passes through it and breaks the circuit, .Fuses ar ordinarily rated as 5A, 10A, 13A, 30A, etc.

Safety Measures whereas mistreatment Fuses

The following cautions ought to be taken whereas mistreatment fuses in home electrical circuits:

(i) Fuses to be used ought to have slightly a lot of rating than this that the electrical appliance can draw beneath conditions.

(ii) Fuses ought to be connected to the livewire so the appliance won’t become live when the fuses has blown.

(iii) turn off the most before ever-changing any fuse.

CIRCUIT BREAKER
The electrical fuse acts as a security device within the same method as a fuse. It

disconnects the provision mechanically if current exceeds the conventional price.

EARTHWIRE
Sometimes, even the fuse cannot capture the high currents coming back from the livewire into the appliance. fastening more protects the user from electrical shock by connecting the metal casing of the applicance to earth. The earthwire provides a secure route from this to flow through, if the livewire touches the casing. we’ll get an electrical shock if the livewire within associate appliance comes loose and touches the metal casing. However, the planet terminal is connected to the metal casing,- that the current goes through the earthwire rather than passing through our body and inflicting an electrical shock. a powerful current passes through the earthwire as a result of it’s a really low resistance. This breaks the fuse and disconnects the appliance.

14.16 style a circuit diagram for a lecture room that desires the subsequent instrumentality in parallel.

(a) One a hundred W lamp operated by one switch.

(b) One lamp fitted with a forty W bulb which may be switched ON and removed from 2 points. .

(c) what’s the advantage of connecting the instrumentality in parallel rather than asynchronous combination.

Ans. The circuit diagram of the half (a) and (b) are going to be,

(c) in an exceedingly shunt circuit voltage remains a similar (240V) across every instrumentality, On the opposite hand, asynchronous circuit voltage across every instrumentality won’t be 240V, however the add of voltages are going to be 240V. Therefore, asynchronous circuit, the equipments won’t work.

SUMMARY

The time rate of flow of electrical charge through any cross section is named electrical phenomenon.

The current thanks to flow of charge that is reminiscent of current thanks to flow of electric charge in wrong way is understood as standard current.

If one coulomb passes through any cross sectional space in one second then current are going to be up to one ampere.

e.m.f. is that the total quantity of energy provided by the battery or the cell in moving a 1 coulomb of position charge from the -ve to the +ve terminal of the battery.

Ohm’s law states that this passing through a conductor is, directly proportional to the electrical phenomenon applied across its ends provided the temperature and physical state of the conductor don’t amendment. Resistance may be a live of opposition to the flow of current through a conductor.

Its SI unit is ohm (Q).

When a possible distinction of 1 potential unit is applied across the ends of a conductor and one ampere of current passes through it, then its resistance are going to be one ohm.

Materials during which electrons will freely move thus on pass electricity ar referred to as conductors, whereas in insulators no free electrons ar obtainable for the conductivity of electricity.

The equivalent resistance Re of a series combination of n resistances is given by Re = R1 + R2 + R3+… + Rn

the equivalent resistance Re of a parallel combination of n resistances is

Galvanometer may be a sensitive instrument that detects current in an exceedingly circuit.

It is continually connected asynchronous with the circuit.

Ammeter is associate electrical instrument that measures larger current.

It is continually connected asynchronous in an exceedingly circuit.

Voltmeter is associate electrical instrument accustomed live electrical phenomenon

between 2 points in an exceedingly circuit.

It is continually connected parallel to a circuit element.

The amount of warmth energy generated in an exceedingly resistance thanks to flow of electrical

current is up to the merchandise of the sq. of current, resistance, and the

tirm interval, i.e. W = !2Rt.

Tl is named Joule’s law.

‘att-hour is that the quantity of energy obtained from a supply of 1 kW : u hour. it’s up to three.6 mega joule (MJ).

1 current that doesn’t amendment its direction of flow is understood as direct ci , rent or d.c.

The current that changes its direction of flow when regular intervals of your time is understood as AC or a.c

SOLVED BOX data

Q.1 however long will it take a current of one0 mA to deliver thirty C of charge? Ans. Solution: .Given that

I = ten mA = ten x 1(T3 A, Q = 30C. mistreatment the formula: ., .

orQ30

I0x10

‘3= 3

Q.2 that metal is employed because the filament of an electrical bulb? make a case for justifiably.

Ans. A metal of high resistance (such as tungsten) is employed because the filament of electrical bulb. once electrons tolerate the filament, they feel larger resistance thanks to that filament is heated and starts glowing

Q.3 A bird will sit harmlessly on high tension wire- however it should not reach and grab near wire. does one grasp why?

Ans. A bird will sit harmlessly on high tension wire as no current passes through its body, since the potential of the wire is constant. However, if the bird grabs the near wire, then thanks to electrical phenomenon of 2, wires, current can flow through the body of the bird and may be fatal.

Q.4 Connect battery to alittle a pair of.5V lightweight bulb and observe the brightness of the bulb. currently add another lightweight bulb asynchronous with the primary bulb. Observe the relative brightness’ of the bulbs compared to once only 1 bulb was lit Repeat the method with 2 or 3 further bulbs asynchronous. mistreatment law of nature, make a case for what happened to the brightness of every bulb.

Ans. Connecting ordinal bulb asynchronous with the first one, it decreases the brightness of 2 bulbs. Adding further bulbs asynchronous with these 2 bulbs can more cut back the glow and brightness of every bulb. In fact, adding a lot of bulbs asynchronous circuit will increase the resistance of the circuit. Hence, consistent with law of nature (V = IR), current through every bulb are going to be reduced that, successively decreases the brightness of every bulb.

Connecting ordinal bulb in parallel with first bulb, the battery of two.5V won’t have an effect on the brightness of the first bulb. Rather, each bulbs can glow with same brightness as in shunt circuit, each bulbs have a similar electrical phenomenon. Adding a lot of bulbs also will not have an effect on the brightness of every bulb. However, brightness of every bulb in shunt circuit is larger as compared to the brightness of bulbs asynchronous circuit.

Q.5 a light-weight bulb is switched on for 40s. If the current consumed by the bulb throughout now is 2400 J, realize the facility of the bulb.

Ans. Given that,

t -40s, w = 2400 J and P = ? mistreatment the formula: electrical energy Power = —— -^

P = q~ = sixty Js” = SOW

Hence, power of the bulb is sixty watt.

CONCEPTUAL queries

14.1 Why in conductors charge is transferred by free electrons instead of by positive charge?

Ans. serious charged protons in conductors (metals) ar certain within the nuclei of atoms. Therefore, {they ar|they’re} not liberated to move within the conductors Electrons gift at larger distance from the nuclei of atoms of conductor are loosely certain. These electrons ar referred to as free electrons wNch will move freely within the conductor and ar means that of charge transfer in conductors.

14.2 what’s the distinction between a cell and a battery?

Ans. Cells convert energy into current. A cell consists of 2 metal electrodes (anode associated cathode) unfit into an solution. teams of cells ar referred to as batteries. Battery stores larger energy as compared to one cell.

14.3 will current flow in an exceedingly circuit while not potential difference?

Ans. consistent with law of nature (V = IR), current passing through a conductor is directly proportional to the electrical phenomenon across the 2 ends of the conductor. Hence, once electrical phenomenon in an exceedingly circuit is zero no current can flow through it.

14.4 2 points on associate object ar at totally different potential difference. will charge essentially flow between them?

Ans. contemplate 2 points A associated B on an object having potential difference Va and Vb. The charge can flow only if the 2 points ar at totally different potential. It means, the charge can flow once potential at .one purpose is more than the potential at the opposite purpose. Thus, charge flows thanks to the distinction of electrical potential.

14.5 so as to live current in an exceedingly circuit, why meter is usually connected in series?

Ans. ‘ so as to live current, meter is usually connected asynchronous with the circuit so most current flows through it (due to its low resistance). If it’s connected in parallel, we have a tendency to cannot live the particular current flowing through the circuit as some current can flow on the opposite parallel path.

14.6 so as to live voltage in an exceedingly circuit, meter is usually connected in parallel. Discuss.

Ans. so as to live voltage in an exceedingly circuit, meter is usually connected in parallel with the circuit. during this method, meter doesn’t disturb this and thence the voltage of the circuit. thanks to high resistance of meter, no current passes through it and thence voltage of the circuit remains unaffected

14.7 what number watt-hours ar there in a thousand joules?

Ans. As we know,

1 watt x 3600s = one watt-hours

3600 Ws = one watt-hours .

3600 joules = one watt-hours

1 joules = – watt-hours

1000 joules = o x a thousand watt-hours

1000 joules = zero.28 watt-hours

Hence there ar twenty eight x 10~2 watt-hours in a thousand joules.

14.8 From your expertise in observance cars on the roads in the dark, ar automobile headlamps connected asynchronous or in parallel?

Ans. Head lamps of vehicles ar connected in parallel. Since, if one head-lamp is out of order the opposite famps still glow. Also, we are able to activate or OFF someone headlight severally, that is barely attainable if they’re connected in parallel.

14.9 an explicit flash-light will use a ten ohm bulb or a five ohm bulb. that bulb ought to be accustomed get the brighter light? that bulb can discharge the battery first?

Ans. to induce the brighter lightweight and discharge the battery 1st, we’ve to use bulbs of resistance five ohm. Lower resistance of bulb means that, larger current can tolerate the filament of the bulb and thence it’ll flow a lot of brilliantly as compared to it of ten Ohm bulb. once larger current passes through the circuit, battery are going to be discharged quickly.

14.10 it’s unworkable to attach ah electrical bulb and an electrical heater asynchronous. Why?

Ans. once appliances ar connected asynchronous, total resistance of circuit will increase. This decreases this and thence the facility through every appliance. so as to avoid this loss of current, and thence of power, through bulb and heater, they’re connected in parallel.

14.11 will a fuse in an exceedingly circuit management, the electrical phenomenon or the current?

Ans. Fuse in an exceedingly circuit is employed to regulate this within the circuit. once current exceeds the restricted price as allowed by the fuse, if burns out, stops this and breaks the circuit.