Current Electricity Questions and Answers

Case 3 In an series LCR circuit power dissipated is given by P V msms cos 1 Xc XL R power is dissipated in the resistor only where tan v so may be non zero in a RL circuit or RC or RCL circuit Even in such cases

Question 4 The given circuit consists of two ideal batteries two fixed resistances and a variable resistance R Resistance R is adjusted so that power consumed by it is maximum Choose the correct option s 6 V Options 12 V R 20 622 wwww R www wwww 302 R 30 Maximum power through R 12 5 W

1 A potentiometer circuit has been set up for finding the internal resistance of a given cell The main battery used across the potentiometer wire has an emf of 2 0 V and a negligible internal resistance The potentiometer wire itself is 4m long When the resistance R connected across the given cell then has values of ii 9 5 Q

it has a wire of low resi 8 In a potentiometer experiment the balancing with a cell is at length 240 cm On shunting the cell with a resistance of 22 the balancing becomes 120 cm The internal resistance of the cell is a 19 b 0 522 c 42 UK PMT 2014 d 2Q

The resistance of a wire is 24 ohm It is so stretched that the new length becomes times Then new resistance of the wire will be 24 se u wore after a fe utan OPTIONS MARK FOR REVIEW CLEAR SELECTION A B 300 450

A wire of area of cross section A is made of metal P and carries current I If density of the wire is p mass of an atom of metal P is m and each atom of P contributes one free electron then the correct expression for drift speed of the free electrons is e charge of an electron

Three equal resistances each of 10 Q are connected The maximum power consumed by each resistor is 20 W The maximum power consumed by the combination is A 60 W 30 W 15 W 10Q2 1022 10 92 B

In the circuit below the cell is ideal with emf 2 V The resistance of the coil of the galvanometer G is 1 Q The steady current through the galvanometer is 452 4 F 4 2V G 122 0 2 A 01 A 5 F 502

R 2 5 A potentiometer wire has length 4 m resistance 8 The resistance that must be connected in series with na to get 330 R za the wire and an accumulator of emf 2 V so a potential gradient of 1 mV per cm on the wire is CBSE AIPMT 2015 d 482 a 320 c 4492 b 40 S2 Core voltmeters of resistance R 1 5 R and come TIM

You have a microammeter which reads 50 A at full scale deflection and the coil in the meter movement has a resistance of 20 ohms By adding two resistors R and R and a 1 5 volt battery you can convert this into an ohmmeter When the two out coming leads of this ohmmeter are connected together the meter is to register ohms by giving exactly full scale deflection When the leads are connected across an unknown resistance R the deflection will indicate the resistance value if the scale is appropriately marked In particular we want half scale deflection to indicate 15 ohms What values of R and R are required how should the connections be made

A heating element is to be constructed from a piece of wire of resistance 600 22 by cutting the wire into a number of pieces of equal lengths and joining these pieces in parallel with a constant voltage source of 240 V The current through each element cannot exceed 2A The maximum power that can be dissipated through such a heating element is A 180W B 1 2kW C 2 4 kW D 3kW

In a uniform solid cylinder of radius R conductivity increases linearly with the distance as we move from the axis to the surface of cylinder from o to 02 Current I enters the cylinder from one end and leaves from the other end Find the current density as a function of distance from axis of the cylinder at any cross section

In the circuit shown here what is the value of the unknown resistance R so that the total resistance of the circuit between points P and Q is also equal to R 1 30 2 399 3 6992 P 30 www 10 2 www R 30 www www

resistance is sm 6 Assertion In case of potentiometer experiment if emfs of both known and unknown batteries are made two times null point length will remain unchanged Reason Null point length does not depend on emf of either of the two batteries null point cannot be obtained if emf of unknown

Find out the equivalent resistance of the given combination of resistors Hence calculate the amount of current flowing through the circuit V1 6 R1 3 R2 R3 R4 6 R5 12 R6 12 R7 R10 3 R9

A uniform wire of resistance R is bent in the form of a ring Four points A B C and D are marked on the ring as shown in figure A battery of emf E may be connected across the ring in two ways Case I Battery is connected between B and D Case II Battery is connected between A and B Choose the correct statement s A In each case same current flows out of the battery B In case I more current comes out of the battery C In case II more current comes out of the battery D In case I the minimum current comes out of the battery A B

A VS 4 A filament bulb 500 W 100 V is to be used in a 230 V main supply When a resistance R is connected in series it works perfectly and the bulb consumes 500 W The value of R is NEET 2016 h 46 Q c 26 92 a 230 Q d 132 tentiometer wire has length 4 m resistance 8 und in series with 10

4 A cube of side having resistance R is cut into equal small cubes If all small cubes are arrange in a series combination then the effectiv resistance of the combination is 1 27R 2 9R 3 R9 4 81R

7 The resistance of a voltmeter is 180 22 When there is 5 V potential difference across its ends it gives full scale deflection What resistance should be connected in series to obtain a full scale deflection at 25 V Talis Ans 720 9

An LCR series ac circuit is at resonance with 10 V each across L C and R If the resistance is halved the respective voltages across L C and Rare a 10 V 10 V and 5 V c 20 V 20 V and 5 V b 10 V 10 V and 10 V d 20 V 20 V and 10 V

wwwwwww Up to n B www www Up to n 1 the smallest resistance that can be obtained by ten resistors

Q1 Judge the equivalent resistance when the following are connected in parallel i 10 and 106 0 ii 1 0 and 103 02 and 106 0 3 Draw a schematic diagram of a circuit consisting of a battery of three cells of 2 V each a 50 resistor an resistor and a 12 02 resistor and a plug key all connected in series and find equivalent resistance 2

52 A wire has a resistance of 5 5 Q at 19 oC and 21 5 Q at 200 oC Find the temperature coefficient of resistivity a of the material 0 016 0C 1 0 160 oC 1 1 600 oC 1 16 00 oC 1 2 points

bulb is plugged into a 120 Volt outlet The resistance of the bulbs is 330 ohms a Calculate the current through the bulb b Calculate the watts and kw c Calculate the cost to run the bulb for 10 hours 8 cents kwhr

terminal potential difference is less than its emf 11 When a current of 2 A flows in a battery from its negative to positive terminal the potential difference across it is 12 V If a current of 3 A is flowing in opposite direction it produces a potential difference of 15 V the emf of the battery is NCERT Pg 111 1 12 6 V 3 14 0 V MERA 2 13 5 V 4 13 2 V olle in parallel by 14 Resistance P clockwise cyclic wheatstone bric power consume and R S is 1 1 1 2 R P 3 R P2 4 Q S 15 A battery of e

Two circular coils of radii r1 r2 and having torns N1 and N2 are connected in parallel across a voltage source The ratio of their magnetic moments is A r12r22 B N1N2xr12r22 C r1r2 D N1N2xr1r2 Your Answer A Answer C Solution M N IA Ni Tr2 i VR VpIAO VA0p 2 rxN M NIVA00 2mry 2 Mar

Paragraph for Question Nos 12 and 13 A circular ring of mass M and radius Rhaving linear charge density on upper half and on lower half is placed on rough horizontal surface A uniform electric field is switched on at t 0 If it rolls without slipping just after field is switched on then Friction force acting on the ring initially is O 4XER 3 M O ER O2 E R Read Less

connected between two plates which are maintained at a constant potential difference V see figure The conductivity of the cylindrical conductor varies across its cross section as G Go where r is the radial 0 distance from the centre axis of the conductor and 00 is a constant The current through the conductor is R to R V L TOR V 2L TO R V 3L L

6 Two wires of equal length and equal diameter and having resistivities p and p2 are connected in series The equivalent resistivity of the combination is Guj CET 2015 a c P P2 2 P1 P2 P P2 b P P2 d P1 P2 l d 4 l d 4 6 500 is connected to

40 Thirteen resistors each resistance between A and B is 4R 2 2 R K www www R www ww R R www www R www B R www ww R www R 3 R ww ww R 4 2R 5 The effective

Current is a measure of A force that moves a charge past a point B resistance to the movement of a charge past a point C energy used to move a charge past a point O amount of charge that moves past a point per unit time E speed with which a charge moves past a point

Q3 Each phase of a balanced three phase connected load consists of a 200 mH inductor in series with the 200 2 resistance Assume zero line resistance and a phase voltage of 200 V at 400 rad s Find a the phase current b the line current c the total power absorbed by the load

The potential difference across 8 ohm resistance is 48 volt as shown in the figure The value of potential difference across X and Y points will be x ww 302 122 YMM 1 160 volt 3 80 volt 2002 2452 13092 600 I 802348V 3 2 128 volt 4 62 volt

DC ammeter has resistance 0 122 and its current ranges 0 100 A If the range is to be extended to 0 500 then the following shunt resistance will be required CG PMT 20 a 0 01022 c 0 025 S b 0 01122 152 d 0 25

An RLC circuit consists of a 48 2 resistor a 200 F capacitor and an inductor The rms current is 2 5A when the circuit is connected to a 120 V 60 Hz outlet What is the inductance in mH 83 68 O 74 O 12 O 51 0 35

Q2 Write the mesh equations for each of the networks of Figure I and II below and using determinants solve for the loop currents in each network Use clockwise mesh currents 7 5k0 www R R 9 1 kn TETI Rs 6 8 km E 5 18 V 1 R 2 2kf 3V R 33 kn 16 V E R www 40 40 E www R 702 m Ro 40 RE 30 12 V ww WN R Bv on

Please answer in two sig fig For the circuit shown in the figure all quantities are accurate to 2 significant figures What is the value of th current 12 V 552 WW 10 Q ww 6 V 302 W 8 V

In the circuit shown in figure if both the bulbs B and B are identical then C 600 F voor L 12 mH 500 B B daw 1 Both bulbs have equal brightness 2 B will be brighter than B 1 3 As the frequency is increased brightness of B will increase and that of B will decrease 4 As the frequency is decreased the brightness of B will increase and that of B will decrease

1 Two batteries of emf 1 and 2 2 1 point 1 and internal resistances R1 and R2 respectively are connected in parallel as shown in the figure Fig i The equivalent emf seq of the two cells is in tween 1 and 2 i e 1 eq 2 The equivalent emf eq is smaller than 1 The eq is given by eq 1 2 always eq is independent of internal resistances R1 and R2 Fig i 11 B

10 The temperature dependence of resistivity p T of semiconductors insulators and metals is significantly based on the following factors this question has two correct answers 2 points The number of charge carriers can change with temperature T Length of material can be a function of T Time interval between two successive collisions can depend on T Mass of carriers is a function of T

8 According to Joule s law if potential 1 point difference across the conductor of a material of resistivity p remains constant then heat produced in the conductor is directly proportional to O 1 P O 1 p O P

12 Kirchhoff s junction rule is a reflection of This question contains 2 corrects answers 2 poin Conservation of current density vector Conservation of charge The fact that momentum with which a charged particle approaches a junction is unchanged as a vector as the charged particle leaves the junction The fact that there is no accumulation of charges at a junction

13 A carbon resistor of 47 4 7 KQ is to be marked with rings of different colours for its identification The colour code sequence will be O Violet Yellow Orange Silver O Yellow Violet Orange Silver O Yellow Green Violet Gold O Green Orange Violet Gold

In a potentiometer arrangement shown the length of potentiometer wire AB is 2 m with switch open the null point is 40 cm from end A and with switch closed the null point is at 36 cm from end A The internal resistance of cell in Qis A 15 0 ww B

A potentiometer wire has length 4 m and resistance 8 The resistance that must be connected in series with the wire and an accumulator of e m f 2V so as to get a potential gradient 1 mV per cm on the wire is A B 480 320

9 An electrical device creates a potential difference of 1500 V across two points at the surface of human skin Dry human skin has a resistance of about 125 000 2 Calculate the current moving through the skin What physical effect will this current most likely have on this person K U T I A 5 Given 1 Formula s Equation s and Answer 2 Statement 2

4 Draw a circuit diagram with a two cell battery and four bulbs connected in parallel Include a switch for controlling each load Include four diagrams showing each bulb illuminated individually K U 4

A 22 0 A current runs through a 12 gauge copper wire through a light bulb How many electrons pass through the light bulb each second O 15 0 x 10 21 O 120 0 x 10 19 O 13 8 x 10 19 13 0 x 10 18

0 In the circuit shown i will be equal to 30 1 1 A 3 4 A 4V 60 www 202 2 2 A 4 0 5 A 20 f f 1 1 A 3 4 A 302 4V 602 ww 20 2 2 A 4 0 5 A

A 2 V battery a 990 Q resistor and a potentiometer of 2 m length all are connected in series The resistance of potentiometer wire is 100 then potential gradient of potentiometer wire is O 0 5 V m 1 0 0 1 Vm 1 0 0 01 V m 1 O 0 02 V m 1