Current Electricity Questions and Answers

In the given circuit r and r are the internal resistances of the cells A and B For what value of R the terminal potential difference of cell A is zero 1 3Q a A wwww r 30 1 5V www R b B www r 19 2V 2 4 2

For what value of the resistance x the totaegr power developed in the external resistors is maximum 1 0 5 3 0 8 H 12v www r 1 5 www X www 12 40 2 0 7 4 1 5

In an electrical arrangement as shown the equivalent resistance between X and Y will be A A 150 8 2 X Yo B 750 80 wwww 10092 509 A 750 D C 950 8 B www 500 C 8x12 21 3 D 850 80 10A 1 42 P 367 A 18 3 49 36 4 3

In the circuit Fig 2 b 34 E F G and H are cells of e m f 2 1 3 and 1 volt and their internal resis tances are 2 1 3 and 1 2 respectively Calculate i the potential difference between B and D ii the potential difference across the terminals and each of the cells G and H FIGURE 2 b 34 A D H 202 wwww H GUDE B C W

ps across 01 2 3 1 1 3 loto 3 2 2 4 lo 1 The density of a piece of a metal of atomic weight 60 is 5 x 103 kg m and resistivity 2 108 m Given that Avogadro s number N 6 10 mol and e 1 6x10 19 C What is the mobility of electrons in the piece of metal Consider one free per atom A 1 5 25 x 10 8 m s v1 2 6 25 x 10 10 m 1v1 3 5 25 10 10 m s 1 4 6 25 x 10 3 m s 1 The resistance of a carbon resistor having colours as in the given diagram is 5 3 2R 3 3R 2 B A 2 3 4 R A conductor with rectangular cross se dimensions a x 2a x 4a as shown i Resistance across AB CD and EF respectively Then 4a 2 10 C 2a a LL

202 The correct circuit for the determination of internal resistance of a battery by using potentiometer s 1 2 3 4 R 4 www R E R E R wyw wwwwww H E EXE 1 CEO125 Ir CO th 1 2 3 2

2 A galvanometer has resistance 100 It gives full scale deflection on passing 10 mA current through it To convert it into voltmeter of range 0 to 10 V the resistance to be added in series is 1 1110 S 2 90 2 3 9000 S 4 900 0

When a particular current flows through a resistance wire a the heat produced will be more if the current is drawn from an AC source b the heat produced will be more if the current is drawn from DC source c no heat will be produced d heat will be independent of source and current

A 200 volt electromotive force is applied to an RC series circuit in which the resistance is 1000 ohms and the capacitance is 5 x 10 6 farad A Find the charge q t on the capacitor if i 0 0 2 q t B Determine the charge at t 0 006 s Round your answer to five decimal places C Determine the current at t 0 006 s Round your answer to five decimal places D Determine the charge as t 00

The figure is made of a uniform wire and represents a regular five pointed star The resistance of section EL is 2 ohm Find the resistance in ohm of the star across F and C sin 18 B F

17 points In the figure the values of the resistors are as follows R1 31 S2 R2 10 12 R3 152 V 47 V I 6A What is the voltage drop from node a to node b Now if you join nodes a and b wire what is the current flowing through that wire from top to bottom Note In this problem you may only submit numerical answers e If 4 is the correct answer 4 will be marked as correct but 2 2 will be marked as incorrect Open Circult and Short Circuit of a simple configuration 1 V R ww Current Voltage of a with respect to b A R3 ww R V O a ob

42 When the current in the portion of the circuit shown in figure is 3 A and is increasing at the rate 1 A s the measured potential difference Va Vb 12 V However when the current is 2 A and decreasing at the rate of 1 A s the measured potential difference Va Vb 3 V The value of R and Lare www b R 1 3 ohm and 2 henry respectively 2 2 ohm and 3 henry respectively 3 2 ohm and 2 henry respectively 4 3 ohm and 3 henry respectively a000000 IL

2 E V V r be V The internal resistance of the cell must be 2 E V r E 1 2 Hint V E IR and V lr calculate B E To draw maximum current from a combination of cells how should the cells be grouped ULES 3 E V r V 4 E V r 1 Series 2 Parallel 3 Mixed 4 Depends upon the relative values of external and internal resistance

15 There are three copper wires of lengths and cross sectional A 1 2 areas L A 2L minimum resistance 2A Which wire has the K SL A a Wire of cross sectional area 2 b Wire having cross sectional area A c Wire having cross sectional area 2A RAL A MA a c T

Consider the circuit shown Entries in List I are some relations for quantities involved in the circuit Match these relations with the entries in List II 7 List I List II P If current through E is zero 1 E E 2 Necessary condition for maximum power in R 2 E E R Terminal potential difference of cell 1 is equal to terminal potential difference of cell 2 3 E E s If current through E is zero 4 R O P 1 Q 4R 1 2 S 2 O P 1 Q 4 R 1 2 3 S 2 OP 1 Q 4 R 2 S 2 3 0 54 1 11 16 21 26 31 36 41 46 Not As 12 17 22 27 32 37 42 41

he heat generated in 50 resistor due to current flowing through it is 10 cal second Heat generated in 4 Q2 resistor in cal s is 452 692 592 ww nswer 0 04 05 6 07 08 O 6 2 11 16

the shown figure if resistance between any two junctions is R then equivalent resistance between A and 8 is 10 Find the value of n A Answer 0 01 B 02 O 2 03 O 32 04 05 04 05 06 O 6 07 07 08 08 O S O 6 11 16 21

fall branches in the shown network is of resistance R 100 then equivalent resistance between A and B is n Q Find the value of n Answer 20 B O 2 C 3 0 05 O 6 07 08 6 116 F B 15

For the circuit shown in figure the voltmeter reads 1 V and the ammeter reads 1 A On inter changing their places the voltmeter reads 2 V and ammeter reads 0 5 A E A Read Less www If another Ris connected in parallel with ammeter in the shown figure then Reading of ammeter will be V MIN A

N 9 The length of a potentiometer wire is 1200 cm and it carries a current of 60 mA For a cell of emf 5 V and internal resistance of 20 the null point on it is found to be at 1000 cm The resistance of whole wire is a 800 b 1200 c 60 d 100 ller of radius R and

Paragraph for Question Nos 15 and 16 For the circuit shown in figure the voltmeter reads 1 V and the ammeter reads 1 A On inter changing their places the voltmeter reads 2 V and ammeter reads 0 5 A Choose the correct option s Resistance of voltmeter is 20 Resistance of ammeter is 70 O Resistance R is 40 O Resistance R is 30 Read Less 6 11 16 21 26 31 36 46

10 To get maximum current through a resistance of 2 5 02 one can use m rows of cells each row having n cells The internal resistance of each cell is 0 5 Q What are values of n and m if the total number of cells is 45 1 m 9 3 n 15 2 m 3 4 m 15

5 The resistance in the three arms of a Wheatstone bridge are respectively 15 10 0 and 22 5 2 When a copper coil is placed in the fourth arm of the bridge at 0 C the bridge remains balanced But to restore the balance of the bridge at 50 C of the coil temperature an additional resis tance r has to be arranged in parallel with the coil What is the value or r temperature coefficient of resistance of copper 0 00425 C 1

For the circuit shown in figure current in A through switch S when it is closed 302 Q 192 wwww www Answer www 192 www P 30 12 V

Four wires each of same length diameter and material and resistance R are connected to each other to form a square A battery is connected across diagonally opposite vertices of the square The ratio of power dissipated in any one side of the square to the total power dissipated is 1 1 1 2 1 2 3 1 4 4 2 1

A resistor of certain resistance R is able to produce 440 J of thermal energy in 22s When an electric current of 2A is passed through the resistor On increasing the electric current to 5A the thermal energy produced in the same time will be 1 1 80 KJ 3 2 75 KJ 2 2 20 KJ 4 3 2 KJ

There is a definite potential difference between the two ends of a potentiometer Two cells are connected in such a way that first time help each other and second time they oppose each other They are balanced on the potentiometer wire at 120cm and 60cm length respectively compare the electromotive force of the cells potentiometer wire at 120cm and 60cm length respectively Compare the electromotive force of the cells

In the circuit shown below if the resistance 5 22 develops a heat of 42 J per second heat developed in 2 22 must be about ww 652 202 M 1 25 1 502 ww 99

Please explain the attached question How is Electric field nversely proportional to the cross sectional area a A steady current flows in a metallic conductor of non uniform cross section of non uniform cross section Which of these quantities is constant along the conductor current current density electric field drift speed

Two cells of equal e m f E b ut of difference internal resistance r and r2 are connected in parallel anc the combination is connected with an external resistance R to obtain maximum power in R find the value of R E r E r R AAAAA

In the part of a circuit shown in the figure the potential difference VG VH between points G and H will be Go 4023 1 6 V 2amp 292 4 3V 193 HO 5V 2 15 V 3 7 V 2amp 3amp 4 3 V

Consider the circuits shown What will the voltage across R1 look like as a function of time in each of them Hint Think about what it is at t 0 and after a long time Circuit 1 www R1 www R2 C Circuit 2 R3 www R1 R2 C

For a generator of armature coil resistance 20 Q with load resistance 10 Q current flowing is 5 amp The efficiency of this generator is 33 33 66 66 76 66

Q 30 A constant current flows through the wire of non uniform area o cross section which of the following will remain constant current density current drift velocity Explain with reason

Q 15 For the given circuit obtain current flowing through resistance R and electric potential at junction 0 www V 15 V R 155 V wwww R 3052 R 4552 2 V 10 V V 8 V A 1 19 A V 12 375 V B 1 1 75 A V 12 15 V C 1 0 175 A V 12 375 V D 1 0 19 A V 1 215 V

A time varying current I is passed through a resistance R as shown in figure 14 310 lo 40 210 310 Which of the following statements is are correct I Average current through the resistance is 111 II The heat generated in the resistance during time interval 1 to 31 is 101 Rt III Total charge flown through the resistance is 111 1 I 0 0 2 A I only B II only

ter arrangement E is the current in primary circuit cell establishing E is the cell to be measure AB is the potentiometer wire and G is a galvanometer Which of the following are essential condition for balance to be the obtained A The emf of E must be greater than the emf of E B Either are positive terminals of both E and E or the negative terminals of both E and E must be joined to one end of potentiometer wire C The positive terminals of E and E must be joined to one end of potentiometer wire D The resistance of G must be less than

copper wire of lengh1 1000 m and cross sectional area A 1 0 mm carries a current 1 4 5 A Find in meya Newton the sum of electric forces acting on all free electrons in the given wire in MN Free electron density and resistivity of copper are 2 5x 10 m and 1 7 10 0 respectively

In an ammeter 0 5 of the main current passes through the galvanometer If the resistan the galvanometer is G calculate the resistance of the shunt in terms of G

closed Then the correct statement is R www w A IfE IR reading of the ammeter is I B If IR E 2IR reading of the ammeter is greater than I C IfE 2IR reading of the ammeter will be zero D Reading of the ammeter will not change

A thin plastic rod is bent so that it is in the shape of a semicircle of radius R 30cm An amount of charge Q 7nC is distributed evenly along the rod What is the electric fielc at the center of the circle

The graph below show the potentiometer experiment depending on the graph below at what value of Lx the galvanometer current lo become zero LX f O c 30 cm O d 100 cm 6v I O e 25 cm G O a there is no equilibrium point O b 50 cm C 2 5v

Three ammeters A B and C of resistance RA R and R respectively are joined as shown When some potential difference is applied across the terminals T and T their readings are I I and I I respectively B A I I I R A B LR 1R 1 Re I R

A galvanometer having a resistance of 500 gives a full scale deflection for a current of 0 05A What is the length in metre of a resistance wire of area of cross section 2 97 x 10 cm that can be used to convert the galvanometer into an ammeter which can read a maximum of 5 A current resistance of the wire 5 x Specific 1072 m

The length of potentiometer wire is Im and its resistance is 492 A current of 5mAis flowing in it An unknown emfis balanced on 40 cm length of this wire The unknown emfis x mv What is the value of 6x 7

A galvanometer of resistance 959 shunted by a resistance of 5 ohm gives a deflection of 50 divisions when joined in series with a resistance of 20k2 and a 2 volt accumulator What is the reciprocal of current sensitivity of the galvanometer in A div 5Q www 95 2 2 V 20 km ww

Four lead acid type of secondary cells each of emf 2 0 V and internal resistance 0 025 are joined in series to provide a supply to a resistan 8 5 The current drawn from the supply and its terminal voltage are respectively a 1 39A 11 87 V b 0 93A 7 9V c 1 39A 7 9V d 0 93A 11 87 V

A battery of e m t E and internal resistance re is connected to a variable resistor R is shown Which one of the following is true E 41 R A Potential difference across the terminals if the battery is maximum where R r B Power delivered to resistor is maximum when R r C Current in the circuit is maximum when R r D Current in the circuit is maximum when

In the potentiometer arrangements shown the driving cell D has emfE and internal resistance r The cell C whose emfis to be measure has emfE 2 and internal resistance 2r The potentiometer wire is 100 cm long If balance is obtained the length AJ 7 D G M 1 2 A 50cm B 50 cm C Balance will be obtained only if resistance of AB is r B

Assertion A Two electric bulbs of 50 and 100 W are given When connected in series 50 W bulb glows more but when connected parallel 100 W bulb glows more Reason R In series combination power is directly proportional to the resistance of the circuit But in parallel combination power is inversely proportional to the resistance of the circuit