Current Electricity Questions and Answers

3 9 V 4 12 V The current capacity of a fuse wire will not depend on 1 Area of cross section of the wire 2 Material of wire 3 Length of wire 4 Current it carries up of the

1 A cell E of emf 6 V and internal resistance 202 is connected in opposition as shown in figure with a cell E of emf 4 V and internal resistance 80 The potential difference across points A and B is E B a 2 V W b 5 6 V

3 A battery of internal resistance 402 is connected to the network of resistances as shown in figure In order that the maximum power can be delivered to the network the value of R in 22 should be A 2 T49 Digit B 3 R wwww R www 6R 4R www C 4 D 1 Electricity

10 Consider a cylindrical element as shown in the figure Current flowing the through element is I and resistivity of material of the cylinder is r Choose the correct option out the following A B 4r 2r 1 2 1 2 1 Power loss in second half is four times the power loss in first half 2 Voltage drop in first half is twice of voltage drop in second half 3 Current density in both halves are equal Electric field in both halves is equal

In a mixed grouping of cells there are m identical cells in a row and there are n such rows Each cell is having emf E and internal resistance r A load resistor R variable is connected to this group of cells Then choose the correct statement out of the following Current through the load R will be maximum if m R n Power transfer to load is maximum when current through R is maximum nE Maximum current through Ris 2r Maximum power transfer to load is n E R 4r

1 4 nswer 4 ver 2 correct 1154 K 1100 K 1400 K 1127 K Bookmark List Q No 1 Question The retarding potential for having zero photo electric current Right Answer 41 Your Answer 3 Difficulty Level low Topic physics modern physics Peer Stat x Unattempted 28 4 Correct 39 1 Incorrect 326 Status Marks Time Solut 1 4 18s Vio

density and Electric field Drift of electrons and the origin of resistivity Temperature dependence of resistivity istivity Paragraph for Question Nos 7 to 9 Consider a cylindrical resistor It is connected to a battery and two points A and B are marked in it in figure The resistivity of the cylinder increases linearly from A to B A B If current at A and B is represented by and I respectively then 2 A B IB 4 Data insufficient 1 A B 3 A B If current density at A and B is represented by JA and JB then 1 JA JB 2 JA JB 4 Data insufficient 3 JA JB If electric field at A and B is represented by EA and EB respectively then 2 EA EB 1 E E

15 In the circuit diagram shown a large number of resistors are connected Using the value of resistances indicated in the figure find the equivalent resistance between terminals A and B 10 A www Be 1 80 2 40 3 3n w 50 www 102 Q www 10 www 22 12 C www 10 8 ww 14 0 18 Q

2 2 figure 8 V 4 V and R 50 If the potential difference between points band a is measured to be 5 V then the value of the resistance in Q is 26 31 36 41 27 32 37 42 28 33 38 43

a large building there are 15 bulbs of 40 W 5 bulbs of 100 W 5 fans of 80 W and 1 heater of 1 kW The voltage of the electric mains is 220 V What will be the inimum capacity in amperes of the main fuse of the building

3 R nr Two sources of equal EMF are connected external resistance R The internal resistances the two sources are 19 and 2 9 If the potent difference across the source having interna resistance 2 9 is zero then R is 1 1 Q 3 2 Q 2 2 3 4 69

city 31 In the situation shown resistances R R and R are in the ratio 3 2 1 then PEKAN PEN h R www www www R www R TH NEM 1 The currents through R R and R3 are in the ratio 1 2 3 2 The rate of heat production in R R and R3 are in the ratio 1 2 3 34 3 The potential differences across R R and R3 are in the ratio 3 2 1 4 The rate of power consumption in R R are

The ammeter A reads 4 A and the voltmeter reads 40 V The value of resistance R is Assuming finite value of resistance of ammeter and voltmeter 3A A www R LOV 252 V 1 Exactly 10 ohm 2 Less than 10 ohm 3 More than 10 ohm 4 Information insufficient 2V ww

galvanometer having a coil resistance of 100 Q gives a full scale deflection when a current of 1 mA is passed through it The value of the resistance which can onvert this galvanometer into ammeter giving a full scale deflection for a current of 10 A is O 20 O 0 10 O 30 O 0 01 Q 21 26 31 36 41 22 42 23 43 44

A vertical ring of radius r and resistance R falls vertically It is in contact with two vertical rails which are joined at the top The rails are without friction and resistance There is a horizontal uniform magnetic field of magnitude B perpendicular to the plane of the ring and the rails When the speed of the ring is v the current in the section PQ is A zero C 4Brv R B D 2Brv R 8Brv X X X

A galvanometer having a coil resistance of 100 gives a full scale deflection when a current of 1 mA is passed through it The value of the resistance which can convert this galvanometer into ammeter giving a full scale deflection for a current of 10 A is 020 O 0 1 0 030 0 010

19 The circuit diagram given below shows the combination of three resistors R R and R3 4Q wwww R Find 1 total resistance of the circuit ii total current flowing in the circuit iii the potential difference across R 32 www R 60 www R3 HE 12 V

A6 V battery of negligible internal resistance is connected across a uniform wire AB of length 100 cm The positive terminal of another battery of emf 4 V and internal resistance 1 Q is joined to the point A as shown in figure If galvanometer shows zero deflection then 6V WW 4V 102 O AC 50 cm O AC AC 50 cm 100 3 cm B

Two wires A and B of the same material and mass have their lengths in the ratio of 2 3 The same potential difference is applied across each of the two wires Determine the ratio of the a current flowing through the resistor A to the current flowing through the resistor B b drift velocity of the electrons in resistor A to the drift velocity of the electrons in resistor B c the specific resistance of wire A to the specific resistance of wire d the heat produced in wire A to that in wire B if the two are connected in a series to a voltage source of voltage V e the ratio of the heat produced in wire A to that in wire B if the two are connected in parallel to a voltage source of voltage V

1 Improper designing or calibration 2 Zero error 3 External conditions 4 Both 1 2 For two resistors R and R connected in parallel the relative error in their equivalent resistance is Where R 10 0 0 1 Q and R 20 0 0 4 9 NCERT Pg 27 0 08 3 0 01 2 0 05 4 0 04 3 Curre 4 Amc 8 The velc V A 9 time Th 1 LT 3 L2T Which dimens

The reactance of the coil is 10 2 and its resistance is 10 Q2 It is connected to an A C source of e m f 220 V The peak value of the current in the circuit is A 44 A 22 A Lees D 22 2 A 22 A

2 A 6 V battery is connected to the terminals of 3 m long wire of uniform thickness and resistance of 100 2 Then the potential difference between two points on the wire separated by a distance of 50 cm will be 1 2 V 3 1V 2 3 V 4 1 5 V

The internal resistance of a cell of emf 2v is 0 122 It is connected to a resistance of 3 90 The voltage across the cell will be a 0 5 v s 1 95 y b 1 9 v d 2 y

2 14 A 6 volt battery is connected to the terminals of a three metre long wire of uniform thickness and resistance of 100 ohm The difference of potential between two points on the wire separated by a distance of 50 cm will be 19 A 1 2 volt 3 1 volt 2 3 volt 4 1 5 volt

The reason for preferring manganin wire in potentiometer is because a of high value of its temperature coefficient of resistivity b of its low resistivity c of low value of its temperature coefficient of resistivity d its magistong door with Jura

15 A uniform conductor of resistance R is cut into 20 equal parts Half of them are joined in series and the remaining half of them in parallel If the two combinations are joined in series the effective resistance of all the pieces is 1 3 RIN 101R 200 dations 2 R 4 201R 200

Two wires AB CD each 1m length carry a total charge of 0 2 microcoulomb each and are placed as shown in figure The ends B C are separated 1m distance Determine the value of electric intensity at the point P in the vector form Note that P is the mid point of BC Small identical balls with equal charges are fixed at wortin B P

D A battery of 20 cells is charged by 220 V with a charging current of 15 A If the emf of cell is 2 V and internal resistance is 0 1 02 then the series resistance required to be in the circuit will be 1 16 2 4 14 92 Hint Net Emf 2 10 92 15 220 20 2 20x01 R 3 12 92 R 1092

In a Wheatstone bridge see fig Resistances P and Q are approximately equal When R 400 22 the bridge is balanced On interchanging P and Q the value of R for balance is 405 2 The value of X is close to JEE Main 2019 1 404 5 ohm PA B D X C 2 401 5 ohm

In the circuit shown in the figure two resistor R and R2 have been connected in series to an ideal cell When a voltmeter is connected across R reading is V 4 0 volt and when the same voltme connected across R its reading is V2 6 0 volt The reading of the voltmeter when it is connected across the cell is V3 12 0 volt The actual voltage across R in the circuit in volt is Correct Answer 4 80 to 4 80 or 7 20 to 7 20 Your Answer 6 Status incorrect R R ww

A galvanometer whose resistance is 50 ohm has 25 divisions in it When a current of 4 x 10 4 A passes through it its needle pointer deflects by one division To use this galvanometer as a voltmeter of range 2 5 V it should be connected to a resistance of JEE Main 2019 2 250 ohm 4 6200 ohm 1 6250 ohm 3 200 ohm

2 Two electric bulbs rated at 25 W 220 V and 100 W 220 V are connected in series across a 220 V voltage source If the 25 W and 100 W bulbs draw powers P and P respectively then JEE Main 2019 1 P 9 W P 16 W 2 P 4 W P 16 W 3 P 16 W P 9 16 IN W 102

The actual value of resistance R shown in the figure is 30 2 This is measured in an experiment as shown using the standard formula R where V and I are the readings of the voltmeter and ammeter respectively If the measured value of R is 5 less then the internal resistance of the voltmeter is V 1 JEE Main 2019 1 570 2 R 2 600 2

6 In the given circuit the cells have zero internal resistance The currents in amperes passing through resistance R and R respectively are JEE Main 2019 1 1 2 R200 R 2002 10 V 10 V 2 0 1

87 of Aalhe series combination of two batteries both of the same emf 10 V but different internal resistance of 20 2 and 5 22 is connected to the parallel combination of two resistors 30 2 and R 92 The voltage difference across the battery of internal resistance 20 92 is zero the value of R in 2 is 20201

1S the conductivity of a semiconducte in 92 m if electron density 5 x 10 2 cm an hole density 8 x 10 3 cm 2 3 V s m 0 01 m V 1g a 5 634 b 1 968 c 3 421 d 8 964 3 A wave is represented by the

The Wheatstone bridge shown in Fig here gets balanced when the carbon resistor used as R has the colour code Orange Red Brown The resistors R and R are 80 9 and 40 respectively Assuming that the colour code for the carbon resistors gives their accurate values the colour code for the carbon resistor used as R would be JEE Main 2019 R R R FR

Q17 An inductor in series with a resistance of 300 2 is connected to a sinusoidal AC voltage supply as shown in the figure What is the resistance of the coil r if the voltmeter reads 7 35 V and the ammeter reads 10 54 mA Inductive reactance of coil XL 534 40 2 Points 148 0 162 90 697 30 448 0 J 4

Four resistances 40 92 60 92 90 92 and 110 9 make the arms of a quadrilateral ABCD Across AC is a battery of emf 40 V and internal resistance negligible The potential difference across BD in V is JEE Main 2020 40 2 A 90 0 B D 40 x 60 2 110 22

7 A 2 W carbon resistor is color coded with green black red and brown respectively The maximum current which can be passed through this resistor is JEE Main 2019 1 20 mA 3 100 mA 2 0 4 mA 4 63 mA

On interchanging the resistances the balance point of a meter bridge shifts to the left by 10 cm The resistance of their series combination is 1 KQ How much was the resistance on the left slot before interchanging the resistances 1 990 2 21 EGO JEE Main 2018 2 505 2

Choose the incorrect statement out of the following The relation V IR applies to ohmic as well as non ohmic conductors The relation E oj applies to all conducting O devices where E is electric field is current density and o is conductivity Resistance of an ohmic conductor is constant at a given temperature Resistance of a non ohmic conductor is a function of applied voltage

2 A resistance is shown in the figure Its value and tolerance are given respectively by JEE Main 2019 Red au Violet Orange 1 27 ks 20 3 27 k2 10 p Silver 2 270 92 5 4 270 92 10

2 In the circuit shown the current in the 12 resistor is JEE Main 2015 6 V 392 1 1 3 A from P to Q 2 0 A 3 0 13 A from Q to P 4 0 13 A from P to Q 292 www 1922 392 wwwww 9 V

5 When a current of 5 mA is passed through a galvanometer having a coil of resistance 15 92 it shows full scale deflection The value of the resistance to be put in series with the galvanometer to convert it into a voltmeter of range 0 10 V is JEE Main 2017 1 1 985 10 2 3 2 535 10 2 2 2 045 10 2 4 4 005 10

JEE Main 2018 Two batteries with e m f 12 V and 13 V are connected in parallel across a load resistor of 10 2 The internal resistances of the two batteries are 12 and 2 2 respectively The voltage across the load lies between 1 11 6 V and 11 7 V 2 11 5 V and 11 6 V 3 11 4 V and 11 5 V 4 11 7 V and 11 8 V

In the given circuit the internal resistance of the 18 V cells is negligible If R 400 92 R 100 92 and R 500 2 and the reading of an ideal voltmeter across R is 5 V then the value of R will be JEE Main 2019 R 1 230 2 R 18 V R www R 2 450 92

Two conductors of equal volumes having no uniform cross section are joined as shown figure The number density of free electrons more in conductor 2 As current passes throug the system Which of the following option correct 0 1 C 50 1 Drift speed of electrons at a Drift speed of electrons at b 2 Drift speed of electrons at c Drift speed of electrons at d 3 Drift speed of electrons at c Drift speed of electrons at a 4 Drift speed of electrons at b Drift of speed electrons at n

Two metal wires of identical dimension are connected in series If o and o are the conductivities of the metal wires respectively the effective conductivity of the combination is 2 3 0 0 20 02 0 0 0 02 0 02 0 02 20 02

When 5 V potential difference is applied across a wire of length 0 1 m the drift speed of electrons is 2 5 x 104 ms If the electron density in the wire is 8 x 1028 m 3 the resistivity of the material is close to JEE Main 2015 1 1 6 10 8 m 3 1 6 10 6 m 2 1 6 107 m 4 1 6 x 10 5 92m dical IIT 1