Current Electricity Questions and Answers

As shown in the figure the emf of the cell is 5 V and the internal resistance of the cell is zero The reading of the ideal voltmeter is 5 V www 10 Q2 O 12V 15 v V V wwwww 30 Q

Using a long extension cord in which each conductor has a resistance 80 a bulb marked as 100 W 220 W is connected to a 220 V dc supply of negligible internal resistance as shown in figure Power delivered to the bulb is x x 121 x 0 44 2 watt Find the value of x I 220V I 852 wwww 82 R 4840

In the circuit shown in the figure the resistance marked R can be varied by using a Rheostat The power across the 5 2 resistor will be maximum if the Rheostat has a resistance equal to 522 4 8 29 14 7 1 59 3 10 9 R www 20 V 022 2 20 Q 4 Zero 35 p i R

6 A frustum of cone having radii 5 m and 2 m of its plane surfaces is kept in a uniform electric field 5 N C perpendicular to the plane faces as shown in the figure The magnitude of electric flux through the curved surface of the frustum is 2 E 5 N C 1 50 Nm C 2 105 Nm C

charges Q and each face of plate A 40 Krop 368 as shown in the figure is Area of 2 32 0 4 8 Q LAE Q O N Q orta 29

20 Among the circuits as shown in the glow intensity of any individual bulb will be minimum in assume all cells to be identical and ideal all bulbs to be identical and no bulb fuses 2 555 4 Hrv V 2v 20 net 2 BATTERIES IN EL N X Series Prons Piel Peons X

A part of a large circuit is shown The values of resistance inductance and capacitance are indicated here Which of the statement s are correct A The charge on the capacitor is increasing with time B The energy of the inductor is increasing with time C The energy of inductor is decreasing with time D The energy of capacitor is decreasing with time 1A 252 2A 2 2 HH 4F IH 1A

Two bulbs consume same energy when operated at 200 V and 300 V respectively when these bulbs are connected in series across a DC source of 500V then A B C D ratio of potential difference across them is 3 2 ratio of potential difference across ratio of power produced in them is 9 4 ratio of power produced in them is 2 3 Correct Answer

A battery of e m f 2 volts and internal resistance 0 10 is being charged with a current of 5 A Calculate the potential difference between the terminals of the battery A B 1 5V 2 5V 11 My Answer Correct Answer

here R3 increased then what will happen 41 In the circuit shown R is increased What happens to the reading of the voltmeter ideal V R www R3 www R www R 1 Increases 2 Decreases 3 First increases then decreases 4 Does not change 44

If a certain piece of copper is to be shaped into a conductor of minimum resistance its length L and cross sectional area A shall respectively be a L 2A b L 2 2A O c 2L 2A d 2L A 2

L The figure shows a simple series circuit of R and R connected to 100 V dc source If the voltag across R is to be measured by voltmeter having a A sensitivity of 1000 n V and b A sensitivity of 20 000 22 V Find which voltmeter will read the accurate value of voltage across R Both meter are used on the 50 V range 100 V 10 k 10 k R R Voltmeter

A ring of radius R and mass M has charge q uniformly distributed on it It rotate with angular velocity w The magnetic moment of the ring will be O 90R 2 O qwR O q R 4 90R

An ideal inductor is connected in series with a resistor and an ideal battery The battery supplies energy at a rate P t the resistor dissipates energy at a rate Pr t and the inductor stores energy at a rate PL t What can be concluded about the relationship between Pr t and PL t PR t PL t for all times t while growth of current PR t PL t for some value of t while growth of current PR t PL t only near the beginning of the growth of current PR t PL t only near the beginning of the growth of current

90 Given R 102 R 202 C 2 F C 4 F The time constants in us for the circuits I II III are respectively ver R R 20 www R wwww R 1 R 8 1 18 5 4 9 2 18 4 8 3 4 18 wwww R II III wwww wwww 119 V II 0 2 MS mundilupe d s

In the circuit shown in figure reading of voltmeter is V when only S is closed reading of voltmeter is V when only S is closed and reading of voltmeter is V3 when both S and S are closed Then R www 1 V3 V V 2 3 V3 V V 2 3R www 6R www E V S 2 2 V V V3 4 V V V3

A cell of internal resistance 102 is connected across a resistor R A voltmeter having variable resistance is used to measure the potential difference across the resistor The plot of voltmeter reading V against G is shown What is value of external resistor R G Resistance of galvanometer A 5 Q 20V 10V 5VY B 402 Z G 0 ww R 24V 10 C 322 D cannot be determined Ans A

29 A resistance wire connected in the left gap c a metre bridge balances a 10 resistance i the right gap at a point which divides th bridge wire in the ratio 3 2 If the length of th resistance wire is 1 5 m then the length of 1 of the resistance wire is 1 1 5 x 10 m 2 1 5 x 10 m 3 1 0 10 2 m 4 1 0 x 10 1 m ak

In step up transformer relation between number of turns in primary coils Np and number of turns in secondary coils Ns are related as ONS Np Np Ns Ns Np O Np 2Ns

The turns ratio Ng Np of an ideal transformer is given as 2 3 If the current passing through the primary coil is 3 A the current in secondary coil is 4 5 A O 15 A 2 A 01 A

9 Voltmeters v and v are connected in series across a d c line v reads 80 V and has a per volt resistance of 200 2 v has a total resistance of 32 k2 The line voltage is 1 120 V 2 160 V 3 220 V 4 240 V

The potential difference between points A and B as shown in the given circuit will be 292 2923 A 292 292 wwww wwwwww 10 v V 20 HH 10 V B hr mis 292

Figure shows graph between and V for two conducto and B Their respective resistances are in the ratio I A 60 1306 1 2 3 1 B 2 1 A V

Sir plz tell whats wrong in this 35 Seven identical cells each of e m f E and internal resistance r are connected as shown The potential difference between A and B is B 1 7E 3 6E A 2 E 4 Zero

The current through the 50 resistance connected across Al as shown in the given circuit is B 202 A 592 2 A 8 V 1 A wwwww 0 5 A 0 2 A 4 V 202

A piece of wire is cut into three equal parts and these pieces are kept together side by side to form a thicker wire Compared to that of the original wire the resistance of the bundle becomes O O O 61 times times times

Three electric bulbs whose resistance are in the ratio of 1 2 3 are connected in parallel to a constant voltage source The power dissipated in them has the ratio O 1 2 9 O 3 2 1 O9 4 1

In the circuit as shown V V V The resistance of each wire AB AC etc are shown E in the figure Select correct option s A current in AC is 6R C PD across CD is B current in AB is 6R D PD across CE is R www 2R www R C 6R www D 6R B 2R wwwwww V

The ammeter A reads 4 A and the voltmeter Vreads 46 V The value of resistance Ris Assuming finite value of resistance of ammeter and voltmeter O Exactly 10 ohm Less than 10 ohm More than 10 ohm wwww R

E E 3 E4 E3 E E 4 E4 E3 E E 32 A part of the circuit is as shown in figure The current in 2 Q2 branch is 10 V 1 1 A 3 0 5 A 49 ww 292 42 2 4 A 4 08 8 V 6 V telegram ne

In the potentiometer arrangement figure the driving cell A has emf and internal resistance r The emf of the cell B is to be rechecked has emf and internal resistance 2r The potentiometer wire CD is 100 cm long If balance is obtained the length CJ is Select the correct option s A 50 cm when r 0 B is independent of internal resistance of secondary cell C 50 cm when r 0 D balanced cannot be obtained A B 2r

The length of a potentiometer wire is 10 m The distance between the null points on its wire corresponding of two cells comes out to 60 cm If the difference of emf s of the cell is 0 4 V then the potential gradient on potentiometer wire will be V m Find the value of k k 3

Three voltmeters are connected as shown 1 B A potential difference has been applied between A and B On closing the switch S select the wrong statement s A voltmeters V increases B voltmeters V decreases C voltmeters V and V3 both increase D one of V and V increases and other decreases B

4 When a 20 12 resistor is connected in parallel with a moving coil galvanometer then its deflection reduces from 75 divisions to 25 division then the resistance of galvanometer is 1 102 2 200 3 40 22 4 60 2

In the circuit shown in figure 17 Q18 A Current through R is zero if R 20 and B 402 In this case select incorrect option s A current though R is 2A B current through R is 3A C both A and B are correct B C 10V 5V A 15V R D CH D both A and B are wrong

Voltmeter reads the potential difference across the terminals of an old battery as 1 40 V while a potentiometer reads its voltage to be 1 55 V The voltmeter resistance is 28002 Then select the correct option s A the emf of the battery is 1 4 V B the emf of the battery is 1 55 V C the internal resistance r of the battery is 300 D the internal resistance r of the battery is 502

The current i in a wire changes with time according to the law i iosin nt The total charge in magnitude crossing through a cross section in the time interval t 0 to t 1 nlo s is given by T io ve constant Find the value of n

In the adjoining diagram at steady state choose the correct option s A the current through the branch CB is 4 amp B the current through the branch CB is 1 amp C energy stored in the capacitor is 0 8x1073 D energy stored in the capacitor is 1 6x10 1 amp 4V 30 3V 2 amp 12 www 2 amp www 302 A ww 552 www 4 F www 20 3 152 452 www

iron wire having length I and area of cross s ection A has resistance of 5 ohm if without charge the temperature the length is double of this wire and no change in its volume the n find the resistance of new wire

When a galvanometer is shunted by a resistance S its current capacity increases n times If the same galvanometer is shunted by another resistance S its current capacity will increase to n What is the value of n in terms of n S and S A B n S S D S n 1 S S YOU C n 1 S S S n 1 S S

A cell of emf and internal resistance r is connected to an external resistance R Efficiency of the power supplied by cell increases to double when R resistance changes from 192 to 302 find r in 2

Four resistors two inductors and an ideal battery are connected in a circuit with the help of three switches S S and S3 as shown in figure Initially switch S is opened and S S3 are closed Now answer the following questions e 0 37 15 The current in the branch BC at t Tis where t is time constant V V A 0 4725 B 0 0275 C 0 2808 R V R yos A 0 8400 V R K www 2R S2 S B wwwwwwwww 2L 2 M S3 20

1 0 4 V 3 0 2 V 28 Current is carried in a wire of length L If th wire is turned into a circular coil The maximu magnitude of torque acting on it when placed a given uniform magnetic field B will be 1 2 2 V 4 1 V LIB 2 L2IB Li B 2 LIB edic

23 Figure 3 34 shows a potentiometer circuit for comparison of two resistances The balance point with a standard resistor R 10 0 2 is found to be 58 3 cm while that with the unknown resistance X is 68 5 cm Determine the value of X What might you do if you failed to find a balance point with the given cell of emf e A R B

18 Two ideal voltmeters an ideal ammeter are connected as shown The battery is non ideal Find the correct plot of A vs x V vs x V vs x where x is distance of slider on rheostat from left end X V B V www DIGITAL V X C A www V A A D

9 In the figure the voltmeter shows reading of 20 V The battery has a voltage of U 100 V no internal resistance Find the ratio of the current going through right part of the potentiometer to the current going through the voltmeter if the jockey divides potentiometer into ratio 1 2 and bigger resistance of the potentiometer is located to the right of jockey CITA U www

107 If the rheostat slider were extreme right to the far left How will the reading of voltmeter V change di V rheostat 1 First increase and then decrease 2 First decrease and then increase 3 Increase continuously 4 Decrease continuously 3 30 1124 NOU 1

50 The force exerted by the conductor AB on the loop CDFG shown in figure is 1 8 x 104 N attraction 2 7 2 x 104 N attraction 3 7 2 x 104 N repulsion 4 4 x 104 N repulsion i 20A B A cm 1 10A D 9 cm 20 cm

105 Two wires have their lengths diameters and resistivities all in the ratio of 1 2 If the resistance of the thinner wire is 10 92 then the resistance of the thicker wire is A 5 C 20 YEU SEV B 10 22 D 40 2

Two cells of the same emf e but different internal resistances r ry are connected in series with an external resistance R I Column I 1 value of current through R 2 when external resistance R is T1 T2 3 when external resistance R is f f 4 when external resistance Ris TI II 11 R www Column II P potential drop across second cell is zero I Q 2e R 1 1 R potential drop across first cell is zero S maximum power output across recistonga P