Current Electricity Questions and Answers

27 In the following circuit the current through the resistor R 2 2 is amperes The value of Iis JEE Adv 2015 Pap R 292 www 6 5 VT 6 92 1292 www 192 www www 252 89 www 492 www www 1092 292 wwww 492

A current loop in a magnetic field 1 can be in equilibrium in one orientation can be in equilibrium in two orientations both the equilibrium states are unstable 3 can be in equilibrium in two orientations one stable while the other is unstable 4 experiences a torque whether the field is uniform or non uniform in all orientations NEET 20

Current Electricity 12 27 V Find the equivalent resistance between A and B Each resisto has same resistance R b 8 a R 5 c R 5 6 R 5 d R w www 13

102 A R R 1552 il A B B D D C R 1052 C m 532 5 Determine electric potential at each of the four nodes ABCD in the circuit Point Electric Potential V M 30V Battery R 2012 6 Determine the net current flow into AND out of each of the four nodes ABCD in the circuit out Point In 3 2 37A 2 36A 1 56A 1 56A 2 37A2 37A 92A 93A 7 Determine the net voltage drop around at least three of the six or so closed loops STION Uco your experimental results to analyze the circuit you built in terms of

In the circuit shown in figure below the current through A the 302 resistor is 1 A B the 32 resistor is 0 2 A C the 40 resistor is 0 50 A D the 4 resistor is 0 25 A 9V 3 292 ins 22 moon 80 wwwwwwwww 252 292

Imagine that you are sitting in a room in which a uniform magnetic field B exists An electron comes from your front in horizontal plane and gets deflected to your left The direction of B in this room is 1 To your right f 9 2 To your left 3 Vertically upward 4 Vertically downwards

In arrangement of resistances shown in the diagram is attached to a constant source of emf s The resistor at the top consists of a wire of length L and resistance per unit length p The top end of the fixed resistor R can be slid along the wire The earthed horizontal wire at the bottom is of negligible resistance and the resistance of the ammeter can also be neglected V is the potential at the point where resistor R is connected and I is reading of ammeter A Choose the correct option 1 1 A D C L Jitraj B D 1 1 V L R L l

Example 3 54 Figure shows three identical bulbs A B and C which are connected to a battery of supply voltage V When the switch S is closed then discuss the change in A B C lo gaite V S i the illumination of the three bulbs ii the power dissipated in the circuit

resistance between the ends of a face diagonal such as a and c a h IL X C C of

128 Potential difference between A and B in the figure shown is 6 V 12 1 2 V 3 8 V 292 ww A www ww 3 9 X 109 ww 2V ww 39 192 2 8 V 4 2 V 4 V

29 In the LR circuit shown what is the variation of the current I as a function of time The switch is closed at time t 0 sec 2V A 1 1 R 1 eL V Rt L 0000 Rt R 3V R ww V B Rt e L None

The internal resistance of a cell of e m f 2 V is 0 1 Q2 It is connected to a resistance of 3 9 2 The voltage across the cell will be a 1 95 V b 1 9 V c 0 5 V d 2 V 1999

17 In the arrangement shown the magnitude of each resistance is 12 The equivalent resistance between O and A is given by a 75 a b 17 02 c B D 275 352

In R L C series AC circuit the potential differences across each element is 20 V Now the value of the resistance alone is doubled then potential differences across R L and C respectively become 1 20 V 10 V 10 V 2 20 V 20 V 20 V 4 10 V 20 V 20 V 3 20 V 40 V 40 V

40 electric bulbs are connected in series across a 220 V supply After one bulb is fused the remaining 39 are connected again in series across the same supply The illumination will be a more with 40 bulbs than with 39 b more with 39 bulbs than with 40 c equal in both the cases d in the ratio 402 392 1989

The switch S is closed at t 0 Just after closing the switch reading of ideal Voltmeter and reading of ideal Ammeter are V volt and I amp respectively The final readings of devices are V volt and 12 amp given R 52 R R3 102 L 10 mH A The value of i is 1 amp V V 1 21 C The value of is 2 ohm 30 V S R www R3 wwww R L 66000000000000 B The value of i is 2 amp V V is 4 ohm 4 21 D The value of

23 In the situation shown the currents through 3 22 and 2 2 resistances are in the ratio 19 www A 39 www 2 7 4 www 49 292 wwwww www 59 3 AY

32 In the situation shown the potential difference across the cell of smaller e m f is 1 2 V 2 4 V 3 Zero 4 6 V 2 V 19 www 10 V www 192 www 292

R in R 32 In the situation shown the potential difference across the cell of smaller e m f is 2 V 19 ww 10 V ww 202

Three point charges 9 92 and q3 are taken such that when q and q2 are placed close together to form a single point charge the force on q3 at distance L from this combination is a repulsion of 2 unit magnitude When q2 and q3 are combined the force on q from same distance L is of magnitude 4 unit and is attractive Also q3 and q combining exerts a force of magnitude 18 unit in q2 from same distance L Algebraic ratio of charges q 92 and q3 is b 2 3 4 d 4 3 2 a 1 2 3 c 4 3 1

A battery of 20 cells each having e m f 1 8 V and internal resistance 0 1 2 is charged by 220 volts and the charging current is 15 A Calculate the resistance to be put in the circuit

Example 3 6 A battery of 10 V and negligible internal resistance is connected across the diagonally opposite corners of a cubical network consisting of 12 resistors each of resistance 1 2 Fig 3 23 Determine the equivalent resistance of the network and the current along each edge of the cube A A A I 2 D 1 2 1 2 D 1 2 I B 1 2 B 31 C 1 2 C

86 A B C D battery Two identical capacitors are connected in series and the combination is connected with a shown Some changes in the capacitor 1 are now made independently after the steady state is achieve listed in column I Some effects which may occur in new steady state due to these changes on the capacitor 2 are listed in column II Match the changes in capacitor 1 in column I with corresponding effect on capacitor 2 in column II Column I A dielectric slab is inserted Cap 1 Cap 2 P Separation between plates increased 9 A metal plate is inserted connecting both R plates The left plate is grounded S Column II Charge on the capacitor increases Charge on the capacitor decreases Energy stored in the capacitor increase pollets festasie No change is occurred

0 A ring is made of a wire having a resistance R 12 22 Find the points A and B as shown in the figure at which a current carrying conductor should be connected so that the resistance R of the sub 8 circuit between these points is equal to 3 4 5 128 c 4 3 a b d 4 1 12 3 1 2 41 O 12

A current passes through a resistor Let K and K represent the average kinetic energy of the conduction electrons and the metal ions respectively a K K c K K b K K d Any of these three may occur

A In the circuit shown the cells A and B have negligible resistances For V 12 V R 500 S and R 100 2 the galvanometer G shows no deflection The value of V B R a 4V c 12 V is VB b 2V d 6V

I shown in fig E F G and H are cells of emf 2 1 3 and 1 volts and their internal resistances JEE 1981 are 2 1 3 and 1 ohm respectively Calculate 1 F D value of n will be E 252 3 D B C HI i The potential difference between B and D is given by 13 n 13 MAHT SHOM ii The ratio of potential difference across the terminals of the cell G to cell H is given by Volt then valu of n will be n 2 19 the

A step up transformer operates on 220 V line and supplies 2 2 A The ratio of primary and secondary winding is 11 50 The output voltage in the secondary is 1 220 V 2 100 V 3 1000 V 4 Zero

A potentiometer is being used to compare two resistances The balancing length for a standard resistor R 10 0 2 is 58 3 cm while that for an unknown resistance X is 68 5 cm Determine the value of X What would you do if you failed to find a null point on the potentiometer wire AB

12 cells each of emf 1 5 V and internal resistance 0 5 2 are arranged in m rows each containing n cells connected in series Calculate the values of n and m for which this combination would send maximum current through an external resistance of 1 5 2 Sample Paper 6 2 R 1 502 H

In a hydrogen tube it is observed that through a given cross section 3 13 x 10 5 electrons per sec moving from right to left and 3 12 x 10 5 protons per sec are moving from left to right The electric current in the discharge tube and its direction is

Find the equivalent resistance between A and B of given wire mesh of 14 resistances each wire having resistance R A R 2 5R 6 C B 2R 3R D 2 H A B

A copper wire has a resistance of 0 5 22 Another copper wire of the same mass as the first one double in length of the first Find the resistance of the second wire

12 Find the potential difference VA VB for the circuit shown in the figure B IV 2 IV 350 1350 192 IV 192 4 19 SIR A

as shown below Arrange Three resistances of equal value are arranged in them in the increasing order of power dissipation different combinations www I III 1 III I N I 3 I IV III II i II IV 2 II III IV I 4 I III II IV

7 Consider building the following resistor a square ABCD of side length and connect the centers of each side to form another square Connect the centers of each side of this square to form yet another square and so on to infinity Assume that all the wires in the circuit have the same cross section and resistivity Resistance of each side of square ABCD is R c A xR 3 A A3 A2 KA4 D D3 B B2 BKB BA B3 D4 D2 D B C4 C2 C3 C If the resistance between opposite corners A and C of the square ABCD is xR x is a numerical factor the resistance between corners A2 and C is a xR C b xR 2 d None of these

An alternating voltage is connected in series with a resistance R and an inductance L If the poten tial drop across the resistance is 200 V and across the inductance is 150 V then applied voltage is 1 350 V 2 250 V 3 500 V 4 300 V

39 In the circuit shown the value of I in ampere is a 1 b 0 60 c 0 4 d 1 5 452 www 4V 492 www 492 492 1 692

A cathode emits 1 8 x 10 7 electrons s and all the electrons reach the anode when it is given a positive potential of 400 V Given e 1 6 x 10 C the maximum anode current is 1 2 88 mA 3 7 2 mA 2 28 8 mA 4 6 4 mA

44 Twelve wires each having equal resistance r are equivalent resistance between the diagonally opposite to form a cube as shown in figure 32 E20 Find the points a and f h b e C g Figure 32 E20

72 In the following circuit if V A B value of resistance X in ohms will be 1 5 2 10 3 15 4 20 OA www 100 2 V HH 5 V X www m the

Circuit shown is in steady state now when switch is closed galvanometer shows no deflection then correct relation is 1 R C R C 21D C R wwww C C R www C 2 R C R C WRF R c

7 Electric current is passing through a solid conductor PQ from P to Q The electric current densities at P and Q are in the ratio Le 2 2 1 4 4 1 1 1 2 3 1 4 2R

27 In the circuit shown the ratio 1 1 is equal to 1 1 1 2 2 1 3 4 3 3 4 3 4 2 5 5 V 10 CI 1 39 80 32 T 2 V 202

Is it possible a Yes b No c Cannot be predicted d Insufficient data to reply 10 A D 15 A 5 A

46 ww W ww E r you R If E 6V r 20 then maximum power dissipa through R is 1 18 W 2 9 W 3 36 W 4 3

b What is the resistance in the following network between A and B A ww 192 192 www 19 B

21 Determine the values of currents I I2 and 13 in the network shown in Fig 2 85 Given that R R 222 R3 122 R4 R5 42 E 5 V and E 10 V Ans I I3 1 875 A I 2 5 A E SE I1 I A www www B R4 11 12 13 WWW R R3 www R 13 11 www R5 Fig 2 85 E 2 12 13 12 13

3 Figure 6 64 shows a balanced Wheatstone bridge R 5Q D Q 50 92 A S 10 22 B G P 100 S2 www C Fig 6 64 a If P is slightly increased the current in the galvanometer flows from C to A b IfP is slightly increased the current in the galvanometer flows from A to C c If Q is slightly increased the current in the galvanometer flows from C to A d If Q is slightly increased the current in the galvanometer flows from A to C Two voltmeters and two resistances are connected as

In Fig 5 52 connected 2 10 2 and R 20 Determine th Illustration 5 32 equivalent resistance between points i A and D and ii as shown Given R and C com B R www E www R wwww R www www R R R C