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Dear students, prepare for physics class 10th chapter 5 long questions. These important long questions are carefully added to get you best preparation for your 10th class physics ch. 5 exams.
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Our database contains a total of 0 questions for physics Short Questions. You’ll prepare using this huge databank.

Question: 1
Explain series and parallel combinations of resistance with the help of diagram.?
Answer: 1
1-53

Series combination;

In series combination resistance are connected end to end and electric current has a single path through the circuits.

Equivalent resistance of series cicvit;

The total vottage in a series circuit divides among the individuals resistance so the sum of the vottage across the resistanceof each individual resistance is equal to the total vottage supplied by the source thus we can write as :

V=V1-V2+V3m (1.4.6)

Where v is the vottage in across the saltery and V1,V2,V3 are the vottage across resistance R1,R2 and R3 resIpectively

V=IR1+IR2+IR3V

V= I(R1+R2+R3)R

We can replace the R1,R2,R3+m+Rn

Question: 2
<div>Explain series and parallel combinations of resistance with the help of diagram.?</div><div><br></div>
Answer: 2
2-53

Series combination;

In series combination resistance are connected end to end and electric current has a single path through the circuits.

Equivalent resistance of series cicvit;

The total vottage in a series circuit divides among the individuals resistance so the sum of the vottage across the resistanceof each individual resistance is equal to the total vottage supplied by the source thus we can write as :

V=V1-V2+V3m (1.4.6)

Where v is the vottage in across the saltery and V1,V2,V3 are the vottage across resistance R1,R2 and R3 resIpectively

V=IR1+IR2+IR3V

V= I(R1+R2+R3)R

We can replace the R1,R2,R3+m+Rn

Question: 3
An electric bulb is marked with 220 V, 100W, find the resistance of the falment of the bulb.if the bulb is used 5 hours daily, find the energy in kilowatt hour consumed by the bulb in one month (30days)?
Answer: 3
3-53

Given data:

V=220v

P=100w

T=5*30=150hours

R=?

Solution:

P=V1

I=V/R

P=V2/R

R=V2/P=(220)2/100

= 220*220/100

= 48452

Energy in Kwh = watt/100*time

=100/1000*150

= 15 kwh

Question: 4
Define specific resistance and prove that R=P L/A?
Answer: 4
4-53

Specific Resistance:

The resistance of one meter cube of a ubstance is called its specific resistance or resistivity it is represented by p.The unit of specific resistance (P) IN OHM meter πm.

At a centain temperature and for a particular substance the resistance R depends at the length of wire

Length of wire:

The resistance R of the wire is directly proportional to length of the wire it resistance will also be doubled and it its length is halved its resistance would become one hall.

Cross sectional area of wire:

The resistance R of the wire is inversely proportional to the area of cross sector A of the wire.

R*I/A =(2)

It means that a thick wire would have smaller resistance than a thin wire,

R *I/A R= P L/A------(4)

From eq (3)

P= R*A/L-----(4)

If we put L=Im and A= Im2 then eq 140

P=R

Question: 5
Length of copper wire is 1 meter and its diameter is 2mm,then find the resistance of this copper wire.Specific resistance copper is 1.69*108?
Answer: 5
5-53

Given data:

Length of wire L=Im

Diameter of the wire d=2m=2*10-3m

Cross sectional area of th wire

A=πd2/4= 3.14*(2*10-3)2 m2/4

A= 3.14*10-6 m2

Specific resistance of copper =1.69*10-3

R= P*L/A= 1.69*10-8 lm *1m (3.14*10-6 m2

R= 0.54*10-2 π = 5.4*10-3 π

Question: 6
Define Ohm's law also write its mathematical equation?
Answer: 6
6-53

Ohm’s law is stated as the amount of current I passing through a conductor is the proportional to the potential difference V applied across its end provided the temperature and physical state of the conductor does not change mathematically,

I *V (OR) VAT OR V=IR

Where R is the constant of proportionality and is the resistance of conductor.

Limitations of Ohm’s law

Ohm’s law is applicable when temperature and physical state of conductor does not change.

Question: 7
<div>The resitance of a conductor wire is 10M if a potential difference of 100 volt is applied across its ends, then find the value of current passing through it in mA.?</div><div><br></div>
Answer: 7
7-53

Solution:

R = 10M π

=10 *10-6 π

V= 100 V

I=?

V= IR

I = V/R

=100/10*106

=10/10-3, 10+3

=10*10-3/1000

=0.01*10-3 A

=0.01mA

Question: 8
<p class="MsoNormal">Define electric current and write its mathematical form?</p>
Answer: 8
8-53

The rate of flow of electric charge through any cross sectional area is called current

I = Q/

Question: 9
<p class="MsoNormal">What is conventional current?</p>
Answer: 9
9-53

Current flowing from positive to negative terminal of a battery due to the flow of positive charges is called conventional current.

Question: 10
<p class="MsoNormal">Difference between e.m.f and potential difference ?</p>
Answer: 10
10-53

Potential differenc across the two ends of a conductor causes the dissipation of olectrical energy into other forms of energy as charge flow through the circuit e.m.f it is the energy supplied by a battery to a unit positive charge when it flows through the closed circuit.

Question: 11
<p class="MsoNormal">What is ohm’s law and mathematics form?</p>
Answer: 11
11-53

The amount of current passing through a conductor is directly proportional to the potential difference applied across the provided the temperature and the physical state at a conductor does not change.

V= IR

Question: 12
<p class="MsoNormal">Difference between conductor and insulators?</p>
Answer: 12
12-53

Conductor one materials through which electricity passes easily

Insulator:

The substance which do not allow to conduct heat and electric current.

Question: 13
<p class="MsoNormal">Define resistance and its unit?</p>
Answer: 13
13-53

The property of a substance which offers opposition to the flow of current through it is called resistance

Unit of resistance : ohm

Question: 14
<p class="MsoNormal">How many walt hours are three in 1000 joules-1?</p>
Answer: 14
14-53

1 Kwh = 3.6 (H)

3.6*10-3 *10,3 j = Ikwh

1000j = 1/3.6*10,3 kwh = I kwh/3.6*k =1.36 wh – 0.28

Question: 15
<p class="MsoNormal">In order to measure voltage in a circuit voltmeter is always connected in parallel discuss?</p>
Answer: 15
15-53

If voltmeter is connected in parallel then due to high resistance it will not effect the current in circuit due to which voltage of circuit will be different across different resistance.

Question: 16
<p class="MsoNormal">Difference between A.C and D.C?</p>
Answer: 16
16-53

If a coil is rotated in a magnetic field a current will be induced in the coil the current that does not charge its direction of flow and is unidirectional is known as direct current.

State joule’s law:

The amount of heat generated in a resistance due to the flow of charges isd equal to the product of square of current I resistance R and his time duration.

Question: 17
<p class="MsoNormal">Can current flow in a circuit without potential difference?</p>
Answer: 17
17-53

No, current in any circuit can’t flow without potential difference between ends of boltary according to ohm’s law current passing through the conductor is directly proportional to potential difference.

Question: 18
<p class="MsoNormal">Write neutral wire?</p>
Answer: 18
18-53

The other wire is maintained at zero potential by connecting it to the earth at the power station itself and is called neutral wire (N).

Question: 19
<p class="MsoNormal">Why diamond is an insulator for electricity but conductor for heat?</p>
Answer: 19
19-53

Diamond is an insulator because it has a very wide band gap and therefore would not have any free electrons to conduct.

Question: 20
<p class="MsoNormal">What is one ampene?</p>
Answer: 20
20-53

If one colomb of charge passes through any cross section in one second then current will be equal to one ampere.

Question: 21
<p class="MsoNormal">How galvanometer is converted into ammeter?</p>
Answer: 21
21-53

Ideal galvonameter should have very small resistance to pass the maximum current in the circuit after

Question: 22
<p class="MsoNormal">How e.m.f of a battery measure?</p>
Answer: 22
22-53

In order to measure e.m.f of the battery we connect voltmeter directly with the temperature of the battery.

Question: 23
<p class="MsoNormal">What is difference between fuse and circuit breaker?</p>
Answer: 23
23-53

A short piece of metal that melts when excessive current passes through it.

Circuit breaker:

A switch that automatically interrupts the current of an overloaded electric current.

Question: 24
<p class="MsoNormal">What will be affected on a specific resistance if length of wire is halved?</p>
Answer: 24
24-53

If its length is halved then its resistance would become one half.

Question: 25
<p class="MsoNormal">How galvanometer is converted into volt meter?</p>
Answer: 25
25-53

Galvanometer is converted into an voltmeter by connecting a suitable high resistance in series with the galvanometer.

Question: 26
<p class="MsoNormal">Write two safety measure that should be taken in connection with the household circuit?</p>
Answer: 26
26-53

Always use fuse for safety measures in household circuit.

Always use earth wire with these appliances whose casing is made up of metals.

Question: 27
<p class="MsoNormal">Differentiate between electric power and kilowatt hour?</p>
Answer: 27
27-53

Electric power:

Electric power is the rate at which electric energy is transferred electric power is measured by capacity and is commonly expressed in megawalts

Kilowatt hour:

Kilowatt hour isa watt of energy equaivalent to kilowatt (1kw) of power expended for one hour of time.

Question: 28
<p class="MsoNormal">Why diamond does not conduct electricity?</p>
Answer: 28
28-53

Diamond is not a good conductor of electricity because there are no free electrons flowing around in the structure of the diamond.

Question: 29
<p class="MsoNormal">Advantages of parallel and series circuit ?</p>
Answer: 29
29-53

Advantages are that you can add more power sources like batteries and increase the force of the out which grants you more power.

Parallel circuit:

In a parallel circuits all the external resistors are supplied the same potential difference which is not possible in a series circuit.

Question: 30
<p class="MsoNormal">What is a earth wire?</p>
Answer: 30
30-53

An earth wire is a wire that goes into the ground to diperse with electricity that excess electricity goes through to prevent a circuit from frying itself.

Question: 31
<span style="font-size:11.0pt;line-height:107%; font-family:&quot;Calibri&quot;,sans-serif;mso-ascii-theme-font:minor-latin;mso-fareast-font-family: Calibri;mso-fareast-theme-font:minor-latin;mso-hansi-theme-font:minor-latin; mso-bidi-font-family:&quot;Times New Roman&quot;;mso-bidi-theme-font:minor-bidi; mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language:AR-SA">Define electric current. In what units it is measured? Discuss briefly the direction of current through the conductor.</span>
Answer: 31
31-53

Electric Current:

`Time rate of flow of charge is called current’.

A charge `Q’ flowing through any cross-sectional area in time `t’, corresponds to a current I that is defined mathematically as

I = Q/t Eq (1)

When charges flow, they can be positive, negative or both. For example the current in metals is due to flow of negatively charged electrons. The current in the beam of a particle accelerator is due to positively charged protons, while in some cases such as gases and electrolytes, the current is due to the flow of both positive and negative charges. Moving charges, whether positive of negative, are referred to as charge carriers. The total current is I=I.+I.

The SI unit of current is ampere and is represented by capital letter A. When one coulomb charge flows through any cross-sectional area in one second, the current is one ampere

1 A = 1 C/s.

Since coulomb is large amount of charge, therefore ampere is also a large unit of current. In real life situations, we deal with small values of current like mille amperes (mA =10-6 A)

Conventional flow of current:

The direction of conventional current is the direction in which positive charges flow.

In conductors (e.g. metals), the actual flow of current is due to electrons which flow form negative terminal to the positive terminal of battery. However, before the discovery of electron, the current was assumed to flow from positive to negative terminal of the battery even for conductors. This assumed direction of current flow is now called conventional current.

Question: 32
<span style="font-size:11.0pt;line-height:107%; font-family:&quot;Calibri&quot;,sans-serif;mso-ascii-theme-font:minor-latin;mso-fareast-font-family: Calibri;mso-fareast-theme-font:minor-latin;mso-hansi-theme-font:minor-latin; mso-bidi-font-family:&quot;Times New Roman&quot;;mso-bidi-theme-font:minor-bidi; mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language:AR-SA">What is potential difference and emf? Differentiate between them.</span>
Answer: 32
32-53

Potential Difference and EMF:

The electric potential at one point can be higher, lower or equal to the potential difference at other point. ` The difference of electric potential between two points is called potential difference’.

For example in an electric circuit which has an electric device (electric bulb) connected across a battery through conducting wires. The charge leaving the positive terminal of the battery has potential energy in device; part of this energy is lost (concerted to other forms of energy). Thus, there is a difference of potential energy per coulomb of charge (q) from once side of the electric device to the other, which is termed as potential difference.

V = U/q

The potential difference developed and maintained by source of electrical energy is called electromotive force (emf of ).

To sustain steady current in a circuit, emf source (A device which converts a non-electrical energy) is required which maintains a constant potential difference across its ends
Question: 33
Define electric current. Give its formula and SI unit. (b) briefly explain the flow of electric current in electrolyte solution. (c0 explain the mechanism of a battery for the flow of electric current.
Answer: 33
33-53
Electric current: the rate of flow of electric charges through any cross sectional area of a conductor is called electric current. The flowing electric charge may be positive or negative, in case of conducting metal wires the electric current is due to flow of free electrons which carry negative charges.
Formula: if Q denotes the amount of charge flow through any cross sectional in time t, the value of I is given by : I=Q/t
Si unit: the SI unit of electric current is ampere which is also called Coulomb per second.
Ampere: the current is said to be 1 ampere if 1 Coulomb charge flows through any cross sectional area in 1 second. 1A= 1C/1sec
Question: 34
What is conventional current? explain it .
Answer: 34
34-53
Conventional current: current flowing from positive to negative terminal of a battery due to the flow of positive charges is called conventional current.
Explanation: before the idea of free electron which constitute current in metals, it was through that current in conductors flows due to the motion of positive charges. Therefore , this convention is still in use. We can understand the concept of conventional current form the following analogies.
We know that when the ends of heated copper wire are at different temperature, heat energy flows from the end at higher temperature to the end at lower temperature. The flow stops when both ends reach the same temperature. Water in a pipe also flows from higher level to the lower level. Similarly, when a conductor is connected to a battery, it pushes charges to flow current from higher potential to the lower potential. The flow of current continues as long as there is a potential difference.
Note: conventional current produces the same effect as the current flowing from negative terminal to the positive terminal due to the flow of negative charges.
Question: 35
How we measure the current ? explain it
Answer: 35
35-53
Instruments: we use different electrical instruments which detect the current in the circuit. Galvanometer and ammeter are some common example of current measuring instruments.
Galvanometer: a device which is use to detect the presence of current in a circuit is called galvanometer.
Or
Galvanometer is very sensitive instrument and can detect small current in a circuit. A current of few mili amperes is sufficient to cause full scale deflection in it. While making the connections polarity of the terminal of the galvanometer should be taken in to consideration. Generally the terminal of the galvanometer with red color shows the positive polarity while that of with black color shows negative polarity.
Ideal galvanometer: an ideal galvanometer should have very small resistance to pass the maximum current in the circuit.
Ammeter: a device which is use to measure the quantity of current is called ammeter.
After suitable modification galvanometer can be converted in series. So the current flowing in the circuit also passes through the ammeter.
Question: 36
What is potential difference. Explain it
Answer: 36
36-53
Potential difference across the two ends of a conductor causes the dissipation of electrical energy into other form of energy flow through the circuit.
Unit: the SI unit of potential difference is volt and it is denoted by V.
Volt: a potential difference of 1 volt across a bulb means that each coulomb of charge or 1 ampere of current that passes through the bulb consumes 1 joule of energy.
1V=1J/1C
Question: 37
What is electromotive force, explain it?
Answer: 37
37-53
It is the energy supplied by a battery to a unit positive charge when it flows through the closed circuit.
Formula: e.m.f = energy/charge
or E=W/Q
Where E is the e.m.f, W is the energy converted from non-electrical forms to the electrical forms and Q is the positive charge.
Unit of emf: the unit of e.m.f is volt which is equal to the JC-1
Volt for emf: if the emf of the battery is 2V, the total energy supplied by the battery is 2 joules when one coulombs of charge flows through the closed circuit.
Electromotive force in battery: for the continuous flow of current through a wire, battery supplies energy tot he charges, The positive charges leave the positive terminal of the battery, pas through the conductor and reach the negative terminal of the battery. As a positive charge enters the battery at it s lower potential point( negative terminal), the battery must supply energy , say Q or the positive charge to drive it to a point of higher potential i.e. positive terminal.
Result: a source of electromotive force converts non-electrical ( chemical, thermal mechanical etc.) energy into electrical energy. When a conductor is connected to a battery , current flows through it due to potential difference.
Question: 38
How we can measure the potential difference in a circuit?
Answer: 38
38-53
Voltmeter: a device which is use to measure the potential difference is called voltmeter.
Explanation: the positive terminal of the battery is connected to the positive terminal of the battery is connected to the positive terminal of the voltmeter and the negative terminal of the battery is connected to the negative terminal of the voltmeter.
Ideal voltmeter: an ideal voltmeter should have very large value of resistance s othath no current passes through it . Voltmeter is always connected in parallel with the device acros which the potential difference is to be measured.
Question: 39
How we can measure the emf in the circuit.
Answer: 39
39-53
In general, e.m.f refers to the potential difference across the terminal sof the battery when it s not driving current in the external circuit. So in order to measure e.m.f. of the battery we connect voltmeter directly with the terminal of the battery.
Question: 40
State Ohm's Law and also explain it.
Answer: 40
40-53
Statement: the amount of current I passing through a conductor is directly proportional to the potential difference V applied across its ends, provided the temperature and the physical state of the conductor does not change.Activity:Take a copper wire of about 50cm length and apply potential difference of 1.5 V from a battery.Measure the current flowing through the wire using an ammeter connected to it in series.Also measure the potential difference across the wire using a voltmeter connected across it.Obtain a set of readings for I and V, by increasing the number of cells.Plot a graph between I and V which will be straight line.if V is the potential difference across the two ends of any conductor, then current I will flow through it . The value of current changes with the changes in potential difference and is explained by Ohm's law.Mathematically: V=IRProportionality Constant: R is the constant of proportionality and is the resistance of the conductors.
Question: 41
Define electric resistance and write its SI unit.<div>(b) what are the characteristics of ohmic and non ohmic conductors</div><div>(c) what is thermistor?</div>
Answer: 41
41-53
Electric resistance (R): the property of a substance which offers opposition to the flow of current through it is called resistance.
Reason: the opposition comes due to collision of free electrons with atom of the conductor . This cause energy dissipation which result in potential drop.
Unit of resistance: the SI unit of resistance is Ohm.
By Ohm's law: V=IR R=V/I
The resistance is said to be one Ohm if a potential difference of one volt applied across the ends of a conductor and one ampere o current passes through it.
Question: 42
Write a note on specific resistance.
Answer: 42
42-53
Specific resistance: the resistance of one meter cube of a substance is equal to its specific resistance . Its symbol is p. Specific resistance is constant for the type of conduction material being calculated.
Unit: the unit of p is Ohm meter.

Question: 43
Write a note on conductors.
Answer: 43
43-53
Conductors: why do we always use metal wires for the conduction of electricity? Because, they are good conductors of electricity and offer less resistance to the flow of current. But how can they conduct electricity with much ease? Metals like silver a and copper have excess of free electrons which are not held strongly with any particular atom of metals. These free electrons move randomly in all direction inside metals. When we apply an external electric field these electrons can easily move in a specific direction. This movement of free electrons in a particular direction under the influence of an external field causes the flow of current in metal wires.
Rise in temperature: the resistance of conductor increases with increase in temperature. This is due to increase in the number of collisions of electrons with themselves and with the atoms of the metals.
Question: 44
Write a note on Insulators.
Answer: 44
44-53
Insulators: all materials contain electrons. The electrons in insulators, like rubber , however , are not free to move. They are tightly bound inside atoms. Hence , current cannot flow through an insulator because there are more free electrons for the flow of current. Insulators have very large value of resistance . Insulators can be easily charged by friction and the induced charge remains static on their surface . Other examples of insulators are glass, wood , plastic, fur , silk etc.
Question: 45
Write a note on series combination of resistors.
Answer: 45
45-53
Series combination: in series combination resistors are connected end to end and electric current h as single path through the circuit. It means the current passing through each resistor is the same.
Effective resistance of series circuit: the total voltage in series circuit divide among the individual resistors. So the sum of voltage across the resistance of each individual resistor is equal to the total voltage supplied by the source.
V=V1+V2+V3..........(A)
Where V is the voltage across the battery and V1, V2 and V3 are the voltage across the resistor R1, R2 and R3 respectively. If I si current passing through each resistor, then from Ohm's law
V= IR1+IR2+IR3
V=I(R1+R2+R3)
We can replace the combination of resistors with a single resistor calle the equivalent resistance Re. Suc ht hat the same current passes through circuit. From Ohm's law
V=IRe
iRe=I(R1+R2+R3)
Re= R1+R2+R3
Thus equivalent resistance of series combination is equal to some of the individual resistances of combination.
If resistance is R1, R2,R3........., Rn are connected in series. Then the resistance combination will be given by:
Re= R1+R2+ R3+....Rn
Question: 46
Write note on parallel combination of resistors.
Answer: 46
46-53
Parallel combination : in this combination one end of each resistor is connected with positive terminal of battery while other end of each resistor is connected with negative terminal. So, the voltage is same across each resistor which is equal to the voltage of battery. i.e
V=V1=V2=V3
Equivalent resistance: in parallel circuit, total current is equal to the sum of the current in various resistance e.g.
I=I1+I2+I3....................(A)
so by Ohm's law.
I1= V/R1, I2=V/R2, I3=V/R3
So eq (A) becomes
I= V/R1+V/R2+V/R3
I= V[1/R1=//R2+1/R3]
We can replace combination of resistors with a single resistor called equivalent resistance Re such that same current passes through circuit.
From Ohm's law
V/Re= V[1/R1+1/R2+1/R3] as I=V/Re
So, 1/Re= 1/R1+1/R2+1/R3
Thus equivalent resistance of this combination is sum of reciprocals of individual resistance which is les than resistance of any cone combination. If R1, R2, R3.....Rn are connected in parallel, then
1/Re= 1/R2+1/R2+1/R3 ......1/Rn

Question: 47
State and explain Electrical energy and Joule's Law.
Answer: 47
47-53
Joule's Law: the amount of heat generated in a resistance due to flow of charges is equal to the producto fo square of current I, resistance R and the time duration t.Formula & derivation: consider two points with a potential difference of "V" volts. If one coulomb of charge passes between these points; the amo8iiint of energy delivered by the charge would be V joule. Hence when "Q" coulomb of charge flows between these two points then, we will get QV joules of energy. If we represent this energy by W, then electrical energy supplied by Q charge W= QV joule.Now current , when charge Q flow in time t , is defined as W=QV.........................(1)also I=Q/tDerived from formula of Q Q=It.............................(2)So the energy supplied by Q charge in "t" second.Put value of Q in equation (1) W=QV W=I*t*V......................(3)This electrical energy can eve converted in to heat and other forms in the circuit.From Ohm's law V=IR........................(4)Put value of "V" in equation (3) W=i*t*V W=I*t*I*V W=I2Rt
Question: 48
Discuss electric power.
Answer: 48
48-53
The amount of energy supplied by current in unit time is known as electric power.
Formula: hence power P can be determined by the formula
Electric power= Electrical power /Time= W/t
Where W is the electrical energy given by
W=QV
Therefore, above equations becomes
Electric power= QV/t= IV=I2R
Where current I is passing through a resistor R, the electric power that generates heat is resistance is given by I2R. The unit of electric power is watt which is equal to one joule per second(1Js-1). It is represented by the symbol W. Electric bulbs commonly used in houses consume 25W, 40W, 60W and 100W o electrical power.
Question: 49
What is kilowatt-Hour? Explain it .
Answer: 49
49-53
Kilowatt-Hour: the amount of energy delivered by a power of one kilowatt in one hour is called kilowatt-hour.
One kilowatt-hour 1 kWh= 1000W*1 hour
=1000W*(3600s)
=36*105J=3.6 MJ
The energy in kilowatt-hour can be obtained by the following formula:
The amount of energy in kilowatt-hour= watt*time of use in hours/1000
The electric meter installed in our houses measure the consumption o electric energy in the units of kilowatt-hour according to which we pay our electricity bills. if the const of one kilowatt-hour i.e. one unit is known, we can calculate the amount of electricity bill by the following formula.
Cost of electricity= number o units consumed*cost of one unit
Cost of one unit * Watt*time of use in hours /1000
Question: 50
What are direct &amp; alternating current . Explain it
Answer: 50
50-53
Direct current: the current which is derived from a cell or a battery is direct current and is unidirectional.
Explanation: the positive and negative terminals of d.c sources have fixed polarity. Therefore level of D.C remain constant with time.

Question: 51
How we can safe supply to house? also explain house wiring.
Answer: 51
51-53
The electric power enters our houses through three wires:
  1. The ground wire(E)
  2. Neutral wire(N)
  3. e wire(L)
Earth wire: earth wire carries no electricity. The earth wire is connected to large metal plated buried deep in the ground near the house.
Neutral wire; the neutral wire is maintained at zero potential by connecting it to the earth at the power station itself. This wire provides the return path for the current .
Live wire: the live wire is at high potential; The potential difference between the live wire and the neutral wire is 220V.
House wiring: the wires coming from power station are connected to electricity meter installed in the house . The output power fro m the electric meter is taken to the domestic electric current .
benefits of fuses: the main boxcontain s fuses of rating about 30A. A separate connection is taken from , the live wire of each appliance . The terminal of the appliance is connected to the live-wire through a separate fuse and a switch. If the fuse of one appliance burns out, it does not affect the other appliances.
Parallel connection of wires: in house wiring all appliances are connected in parallel with each other. This means they all get the full mains voltage and one can turn ON any appliance without having to turn ON another.

Question: 52
What are Hazard of electricity?
Answer: 52
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Hazard of electricity: our body is a good conductor of electricity through which current can easily flow. Therefore, if a person holds live wire, current will start flowing to the ground while passing through his body which may prove fatal for the person.
Question: 53
What are the safe measures in using electricity in homes. Explain the function of safety devices.
Answer: 53
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Safe use of electricity in homes: in order to protect persons, devices and property from the hazard of electricity there is a need of extensive safety measures in household electricity. Take much care to use fuses and circuit breakers in an electric circuit as safety devices. They prevent circuit overloads that can occur when too many appliances are turned On at the same time or when a short circuit occurs in one appliance.
Safety devices: the fuses m circuit breakers and eart hwring act as safety devices. These prevent overloading and short circuiting.
Fuse: a fuse is a short and thin piece of metal wire which is connected in series with the live wire in a circuit to protect the equipments when excess current flows. If excess current flows from fuse then due to heating effect the wire melts and breaks the circuit before the wire become very hot and causes fire.
  1. Fuses to be used should have slightly more rating than the current which the electric appliances draw under normal conditions. For example, for a lighting circuit choose a 5A fuse as the current drawn by each lamp is very small( about 0.4A or a 100W lamp). In such circuit, 10 lamps of 100 W can e safely used as the total current drawn is only 4 A which can be calculated using formula P=VI. A feq fuses are shown in figure.
  2. Fuses should be connected to the live wire so that the appliance will not operate after the fuses have blow.
  3. Switch off the main before changing any fuse.