Current Electricity Questions and Answers

c both are out of phase by 120 d both are out of phase by 180 V V sinoor 16 The phase relationship between current and voltage in a pure resistive circuit is best represented by VI Ja Ja K 7 In an ac circuit Yand Lori a b c d VI UN 07 01 of 21 22 23 24 C

A beam contains 2 108 doubly charged positive ions per cubic centimeter all of which are moving with a speed of 10 m s The current density is 6 4 A m 9 2 3 2 A m 3 1 6 A m 4 None of these 252 AAA B 24

ii a Calculate the mutual inductance between two coils when a current of 4A in first coil changes to 12A in 0 5s and induces an EMF of 50mV in the other coil b Also calculate the induced EMF in the second coil if current in the first changes from 3A to 9A in 0 02s

300 C of electricity on solution deposited 2 977 of metal with atomic mass 106 4g mol the charge on the metal cation is passing through the electrolyte a 4 b 3 c 2 During electat d 1 in of H and 02

Q2 Two ribbons are given with the following particulars Ribbon Alloy Length m Width mm A Constantan 5 456 1 0 0 03 Negligible Thickness mm Temp coefficient of resistivity C Resistivity m 4 9 x 10 7 B Nichrome 4 235 2 0 0 06 Negligible 1 1 x 10 6 For a fixed voltage supply which of the two ribbons corresponds to a greater rate of heat production

a rate of chemical energy consumption of the cell b rate of energy dissipation inside the cell c rate of energy dissipation inside the resistor d power output of the source resistance 0 10 is connected across a resistor in series with a very low resistance ammeter When the circuit is switched on the ammeter reading settles to a steady value of 2 0 A what is the steady Current Flity 2

60 An L R circuit is connected to an AC source of 50V rms and frequency 50Hz If the power consumed in the resistor is 150W and the wattless component of the current is 4A then the across the inductor will be voltage rms 1 10V 5 2 20V 3 30V 4 40V VS 9

An electric current passes through non uniform cross section wire made of homogeneous and isotropic material If the ja and je be the current densities and EA and Eg be the electric field intensities at A and B respectively then A IA JB EA E B JA JB EA E C JA JB EA EB D JA IB EA EB

one mark for wrong answer A table is given at the ene AC VOLTAGE APPLIED TO A RESISTOR Alternating voltage V is represented by the equation a V t Ve b V t V sinot d V t V tancof c V t V cotuot where Vis the peak voltage A 100 2 resistor is connected to a 220 V 50 Hz ac dua of current in the circuit is 8 The volt V The ave a

a zero b L c 2L d 3L 92 The energy stored in an inductor of self inductance L henry carrying a current of I ampere is a 2 1 6 L7 c LF 8 L 1

no he 12 V 57 Equivalent resistance in 92 between points A and Bis Given r 10 22 www www r www r ww www www r ww 10 9 r www ww B A 58 The equivalent resistance in 2 between points A and B would be

Radii of conductors 1 2 as shown below are r 2r If the resistivity of their materials are same and equal to p then current drawn from the battery will be O 4 E 5pl 8 E 5pl 2 E 3p 4 E 3p h Marks 4 1

34 In the case of forward biasing of PN junction which one of the following figures correctly depicts the direction of flow of carriers a c P P IIIII 1111 V N N b d P P 11111 volt 11111 N N

54 In the circuit shown the resistance of each resistor is 10 92 then the equivalent resistance in 2 between points A and B is A www ww www ww wwww www B

13 The wires which connect the battery of an automobile to its starting motor carry a current of 300 A for a short while What is the force per unit length between the wires if they are 70 cm long and 1 5 cm apart Is the force attractive or repulsive

A wire of cross sectional area 5x10 7m carries a current of 2A If number of free electrons per unit volume is electrons is e 1 6x10 19 coulomb 034 23 125x10 5 m s mood 34 1020 the drift velocity of the 1234

Two bateries are connected as shown in figure Then the reading of voltmeter V is 10V 302 1 2 4 Correct Answer 1 Your Answor 3 Status incorrect 0 8 V 16 V 0 8 V 16 V 8V 202

A wire of irregular shape turning into a circular shape in a magnetic field which is directed into the paper The direction of induced current is a along abcda b along adcba c into the plane of the paper d out of the plane of the paper Blectroma a c

3 A small town with a demand of 800 kW of electric power at 220 V is situated 15 km away from an electric plant generating power at 440 V The resistance of the two wire line carrying power is 0 5 per km The town gets power from the line through a 4000 220 V step down transformer at a sub station in the town a Estimate the line power loss in the form of heat b How much power must the plant supply assuming there is negligible power loss due to leakage c Characterise the step up transformer at the plant

See the electrical circuit shown in this figure Which of the following equations is a correct equation for it R www 81 www 12 2 1 1 1 R ir 0 2 Eg igra 1 1 0 ii R

Figure shows a network of capacitors and resistances in steady state Potentials of some of the points are given Then Potential at M 2 6 V Potential at N 1 6 V Charge across 2uf capacitor is 8 4 C Charge across 2uf capacitor is 4 2 C A B C D 3V 96V 12 201113 192 M 202 www 2 f 4 2 3 302 Janne 11 402 www 2 10V luf 452 43 181 12

When switch S in the figure Figure 1 is open the voltmeter V of the battery reads 3 07 V When the switch is closed the voltmeter reading drops to 2 90 V and the ammeter A reads 1 60 A Assume that the two meters are ideal so they don t affect the circuit Figure V r E ww 1 of 1 Part A Find the emf E Submit Part B VAXO Request Answer Find the internal resistance of the battery

an ionic solution a current consists of rm Ca 2 ions of charge 2e and rm CI ions of harge e traveling in opposite directions Part A If 5 06x10 8 rm CI ions go from A to B every 0 630 rm min while 3 25x1018 rm Ca 2 ions move from B to A is the current in rm mA through this solution I Submit Part B VAZO 4 Request Answer rm mA In which direction from A to or from B to A is the current in part A going

A cylindrical tungsten filament 17 0 cm long with a diameter of 1 10 mm is to be used in a machine for which the temperature will range from room temperature 20 C up to 120 C It will carry a current of 11 0 A at all temperatures Resistivity of tungsten at 20 C is 5 25 x 10 8 2 m the temperature coefficient of esistivity at 20 C is 0 0045 C Part A What will be the maximum electric field in this filament Express your answer using two significant figures E Submit Part B VAXO Request Answer d O W V m

sphere of radius 2R is joined to 5 a charged conducting sphere of radius R carrying a charge Q The charge which flows between them is 1 2 20 4 1 2 2 3 0 3 G L 2R FFICE ST for the first aid a fer 32 After charge redi s inbutils R On 2 10 2 G2A 2A 1 FRIE 3 4 12 2 q to ot 1

An electrical conductor designed to carry large currents has a circular cross section 2 90 mm in diameter and is 15 0 m long The resistance between its ends is 0 100 V Part A What is the resistivity of the material p Submit Part B VAE Request Answer no 2 m If the electric field magnitude in the conductor is 1 21 V m what is the total curren

A cylindrical tungsten filament 17 0 cm long with a iameter of 1 10 mm is to be used in a machine for which the temperature will range from room temperature 20 C up to 120 C It will carry a current of 11 0 A at Il temperatures Resistivity of tungsten at 20 C is 25 x 108 2 m the temperature coefficient of esistivity at 20 C is 0 0045 C R Submit Request Answer Part C What will be the maximum potential drop over the full length of the filament Express your answer using two significant figures VAZO C S2

33 In the circuit shown below the resistance are given in ohms and the battery is assumed ideal with emf equal to 3 0 volts The resistor that dissipates the most power is 3 0V a R c R3 4022 wwww R wwwww R 400 R3600 b R d R4 www R43002 R 2002

39 In the circuit shown the value of I in ampere is 170 4 2 0 69 3 1 0 4 1 5 452 492 ww 4V 40 www 1 612 VAN X 4 10 39 Geita na after t Is i K 6 4 322 1 0 4 2 0 69 3 1 0 4 1 5 www 2 40 4V Rey 42 Ind They current Iry supper 41 be 0 6 A 1 80 middle band will be It De fact as a ford DES 1

Current amperes 12 10 4 2 2 3 45G Resistance ohms The graph at left in the RI plane shows the current I in amperes for a circuit with a resistor having Rohms of resistance W he significance of the value 4 shown by the dotted line R 7 A 9 A The current for a resistor with 0 ohms of resistance is amperes 3 The current reaches a minimum when the resistor has a resistance of 4 ohms As the current becomes large the resistance becomes approximately dohms 3 As the resistance becomes large the current becomes approximately 1 amperes

44 In the circuit shown the current resistor is 1 A The potential difference between points A and B is K 5 1 2 V 3 3 20 V 4 25 V 492 ww 10 92 www 352 www 652 www 292 www A 1 2 216 100 592 www 0 B X Cou MA

In the circuit shown in figure the battery has negligible resistance Switch S is closed at t 0 Maximum current through battery is equal to Imax at time to Value of Imax is mE m n E I and they are coprime Find the value of n m n wwwwwv000 R 122 L 1 2 H wwwww R 19 C 1 F

ring having negligible resistance is used to connect four resistors a V resistances 8R 6R 6R and R as shown in the figure Find the equivalent resistance between points A B A 6R 6R www R wwww B

Q The number density of conduction electrons in a copper conductor estimated is 8 5 x 1028 m 3 How long does an electron take to drift from one end of a wire 3 0m long to its to its other end The area of cross section of the wire is 2 0 x 10 m and it is carrying a current of 3 04

Two wires made of different materials have the same uniform current density They carry the same current only if A their lengths are the same 3 their cross sectional areas are the same C both their lengths and cross sectional areas are the same D the potential differences across them are the same E the electric fields in them are the same

tion 47 In the given potentiometer circuit length of the wire AB is 3m and resistance s R 4 50 The length AC for no deflection in galvanometer is A 2m B 1 8m C dependent on r D None of these Ans A A E 5V r 0 50 F 3V www R 4 50 C

In a conductor carrying a current we expect the electron drift speed to be A much greater than the average electron speed B much less than the average electron speed C about the same as the average electron speed D less than the average electron speed at low temperature and greater than the averag electron speed at high temperature E less than the average electron speed at high temperature and greater than the averag electron speed at low temperature

The current is zero in a conductor when no potential difference is applied because A the electrons are not r B the electrons are not moving fast enough C for every electron with a given velocity there is another with a velocity of equal magnitude and opposite direction D equal numbers of electrons and protons are moving together E otherwise Ohm s law would not be valid

The current density is the same in two wires Wire A has twice the free electron concentration of wire B The drift speed of electrons in A is A twice that of electrons in B B four times that of electrons in B C half that of electrons in B D one fourth that of electrons in B E the same as that of electrons in B

Why Rundur About Us Blog UZ W resistance between point A and B for network is each branch has resistance R B2 2 R 3 R 5 valent resistance between the points AR Theresiance between punt A and for towing network is Inach branch has resistance sind always Answer

Question 25 192 12 V 202 A www 192 Calculate VB B 5V 292 6 V 3 V M M 4 00 B 352 N M 1 00

ving Chu a 210 mA c 420 mA b 155 mA d 75 mA 2 In the given circuit a galvanometer with a resistance of 70 2 is converted to an ammeter by a shunt resistance of 0 05 S2 total current measured by this device 592 ww 70 52 0 05 92 5V is a 0 88 A b 0 77 A c 0 55 A d 0 99 A meter having a resistance of 50 2 gives defle Ris a c 97 The am Ro

E CENTER Shown is a DC circuit that contains two switches Each switch has zero resistance when closed All of the connecting wires should be considered to have zero resistance All of the resistors shown are identical The circuit contains an ideal ammeter and an ideal voltmeter The diagram shows the switches open Below the diagram are four different switch configurations for the circuit Aww www ww wwwww A i i i id a I S V Configuration 1 a b open open closed closed S2 open closed open closed Rank these configurations in terms of the ammeter reading voltmeter B i i i id C vc V V V Vd a reading D vc Vd Vb Va

12 An arrangement consisting of slabs is shown in the figure When system is placed in situation a with temperature difference is maintained between 1 2 equivalent thermal conductivity of system is K and when system is changed to situation b and temperature difference is maintained between 3 4 then equivalent thermal conductivity increases by 20 Find number of slabs in the arrangement d d k 2k 26 a nk nl 2 21 nl d k 2k nk d 4 daxhr

ves The ross the ad a 7 97 The value of current in the given circuit if the ammeter is a galvanometer with a resistance RG 50 52 is 322 5V a 0 048 A c 0 061 A b 0 023 A d 0 094 A 98 A galvanometer coil has a resistance of 15 2 and

3w An uncharged capacitor is connected in circuit as shown in figure Power ratings of bulbs are given At t 0 switch is closed C B Po Vo B Po Vo B Po Vo 3Po 2 A At t 0 just after switch is closed power consumption in circuit is B After a long time power consumption in circuit is Po 2 C Brightness of B decreases with time D Initially brightness of B is less than B but later B will be brighter 0

98 A galvanometer coil has a resistance of 15 2 and the metre shows full scale deflection for a current of 4 mA To convert the meter into a voltmeter of range 0 to 18 V the required resistance is a 5885 92 in series b 4485 2 in series c 5885 2 in parallel d 4485 92 in parallel galvanometer of resistance 509 is connected to

Specific res b 6 d 1 5 c 3 94 The conversion of a moving coil galvanometer into a voltmeter is done by a introducing a resistance of large value in series b introducing a resistance of small value in parallel c introducing a resistance of large value in parallel d introducing a resistance of small value in series ameter of resistance 10 22 gives full scale

a b 1 4 0 c 2 8 2 d 28 0 87 If the current sensitivity of a galvanometer i doubled then its voltage sensitivity will be 88 a doubled c unchanged b halved d four times moving coil galvanome

6 Two moving coil metres M and My have the following particular R 10 52 N 30 A 3 6 x 10 m B 0 25 T R 1492 N 42 A 1 8x 10 m B 0 507 The spring constants are identical for the two metres What is the ratio of current sensitivity and voltag sensitivity of My to M a 1 4 1 b 1 4 0 c 2 8 2 d 28 0