Current Electricity Questions and Answers

MATCHING TYPE WITH 3 COLUMNS 4 ROWS The following table has 3 columns and 4 rows Based on table there are THREE questions Each question has FOUR options A B C and D ONLY ONE of these four options is correct First column shows a circuit diagram second and third column contains steady state charge on capacitor and time constant for the circuit respectively Column 1 Column 2 1 E 1 1 ww R R R C R C wwwwwww R R www www R 0 H CV iii CV P Q Column 2RC 5 RC R RC

E The current in 25 12 resistor is List 1 The resistance of unknown resistor Rin 02 is The equivalent resistance across AB in is 200 B then the value of k is The potential drop across 120 2 resistor is volts then the value of k is W UE Q R IV S BRE P Q NIU 11 PS 51 U IV T ampere f 2 P Q List Il 100 200 3 R 500 S 300 2502 50 U 200 120 C 160 c www 180 2 the net gument through the source battery is 6 ampere then which of the following is correct Optiges D U Q P IV S the ecument through the source battery is 8 ampere then which of the following is correct ATQ0N

5 The galvanometer cannot be used as an ammeter to measure the value of current in a given circuit Which of the following statement s is are incorrect about given information a Galvanometer gives full scale deflection for a small current b Galvanometer has a large resistance c A linear scale cannot be designed so that I d A galvanometer can give accurate values

A zener diode provides 6 V voltage to load resistance R If current by battery may vary from 0 to 100 mA what should be the value of R 9V R www 1 90 2 2 20 3 30 S R 4 40 S

Two cells one of 2 V and internal resist ance 1ohm and another of 1 5 V and int ernal resistance 3 ohm drive the curren t through an external resistor of 10 ohm connected between the common positi ve and negative terminals Find the p d across the external resistor

7 Twelve identical wires of resistance 6 Q each are arranged to form the edges of cube A current of 40 mA is led into the cube at one comer and out at opposite comer Calculate the pd developed between these comers and the effective resistance of the circuit Ans 0 2 V 50

A wire of uniform cross section c onnected to a 10V battery is repla ced by a wire the shape of a long frustum with length same as bef ore Then which statement is tru e regarding the electric field along the wire 1 will change as area of cross sec tion is changing along the length of wire 2 remains same as potential diffe rence across the ends is same as before 3 can t be predicted as data is no t sufficient 4 none of these

SC0077 An npn transistor operates as a common emitter amplifier with a power gain of 60 dB The input circuit resistance is 10002 and the output load resistance is 10 kn The common emitter current gain is JEE Main 2019 April 4 10 1 60 2 104 3 6 10

A battery of emf 10 V is connected to the network of resistances as shown in the figure The potential difference between A and B VA VB is A 2 V 45V B 2 V D 20 29 11 V 152 A 352 B 302 www 10V

The ammeter A and voltmeter V in the given circuit are ideal but the galvanometer has a resistance of 2 In steady state A no current flows in G B 0 1 A current flows in G 4e charge on 1 F capacitor is 1 C D terminal potential difference across battery is 1 8 V 802 1 F 2V V www 202 80 F 1002 A

Consider the circuit shown in the figure La Find the current i flowing through the circuit when the key K is open and K is closed 2 36 A b Find the net charge on the capacitor when K is open K is closed and also when K K both are closed Ou c What is the change in the current i when K is closed 0034 A 1 802 A 1022 1 3 16 12 D o trwww 10V 222 2 24 2 C

iii A 24V battery is connected to a lamp with a resistance of 2002 How much current will flow write the unit in answer iv What voltage battery would be needed to make a 0 5A current flow through a 10 Q2 resistor

If a wristance of 10 Ju 5 H ierough a switch s to a dired supply of doned calculate S2 us connected in it current thro esistor at too 45 in the rate of change of current et t bas with the initial rate of charge of current iny voltage asson the resister at t 27 100v The switch vy time required to reach current upto 80 of its moix value in time kriod for which V V

22 Neglecting the currents taken by the voltmeters V and V calculate a total current taken from the supply b readings on voltmeter V and V Ans 15 A 14 V 16 VJ 30 V de Supply www V www 1 4 ww V

A battery of emf E 12 5 V is connected across a 4m long uniform wire having resistance 492 m Two cell of small EMFs 2V and 4V having internal resistance 20 and 6 respectively are connected as shown in the figure If galvanometer shows no deflection at the point N the distance of point N in m from the point A is equal to Eo A 1 r1 52 12 R 40 www wwG N B

Using Kirchhoff s laws with the electric circuit shown Find the indicated currents in A 1 12 and I 1 01 3 0 113 12 ANY B 12 2 024 0 12 13 1 07 2 012 3 013 0 12 V 1 00 3 011 www 3 00 s www 2001 400

28 Two point charges Q and 2Q are fixed on X axis at positions a and 2a from origin respectively At what positions on the axis the resultant electric field is zero 2 Only x 2 a 4 Only x 3a 2 2 a 3 Both x 2 a 1 Only x

d in battery when one path is broken if 3 paths were originally there why does it happen so Current 0 90 A Current 0 90 A Current 0 90 A Current 0 90 A C Current Current Current 2 70 A

In a Wheatstone s bridge the four resistanc e arms of the bridge are AB 2 ohm BC 3 o hm CD 4ohm and DA 1ohm of emf 2V an d negligible internal resistance is connected across AC and a galvanometer of resistanc e 10ohm is connected between B and D Fin d the current through the galvanometer

Two wires that are made up of same material have length in ratio 4 3 and area of cross section in ratio 5 4 When wires are connected in parallel across a voltage source the ratio of current flowing through them is 1 3 66 7180 16 15 2 4 15 616 55 16

Using superposition theorem find the current through the 40 resistor in the circuit All are in ohms Ans 0 707A resistances downwards 50 V 20 Luing min 40 10 V Using the superposition principle find the voltage across 1k resistor in the circuit Assume the sources to be ideal Ans 3V 1 kn 15 V 25 V

Using nodal analysis find currents in all the branches of the circuit Answer I 6 03A I 2 32A I3 1 65A L 1 3A Is 1 02A I6 0 95A 10 A 13 592 ww 1 2 392 2 19 4 3 15 16 502 2227 4 492 2 A

When a piece of aluminium wire of finite length is drawn to reduce its diameter to half its original value its resistance will become 1 two times 3 eight times EE E 2 four times 4 sixteen times

The network shown in the figure consists of five resistors of resistances P Q R Find the equivalent resistance between A and B Use this technique to find th Chat equivalent resistance when a b PR QS c d P Q R S G r P Q R S r G P Q r R S r and G 0 P 122 Q 22 R 222 S 42 and G 5 22 A 10 www S B

Identify the incorrect statement from the following For accurate easurements a potentiometer wire must a have a uniform cross section b be homogeneous c have high specific resistance d have a high temperature coefficient of resistance

Select one a Ved IsRs ww Vs Select one a Ved 15R5 O b Vs Vdb R hoose the wrong statement www R www b www R2

A 240 V dc shunt motor takes 10A and 30A at no load and full load respectively It is having armature resistance of 0 4 ohm and field resistance of 120 ohm Considering iron friction and windages losses are negligible Then examine the various parameters 1 armature current at no load and full load condition 2 Back emf at no load condition 3 Back emf at full load condition 4 Ratio of back emf from no load to full load condition

Potential difference between point A and point B is 892 B 692 www www 1 Question Type Single Correct Type 20 7 V 27 V 40 V 4 52 A 3 92 www wwww 10 10V

A pole induction motor is working on three phase 50 Hz AC supply at no load and at full load When it runs at no load it has slip of 4 and when runs at full load then slip is 3 By considering these conditions solve the following 1 Synchronous speed of induction motor 2 Rotor speed at no load 3 Rotor speed at full load 4 Determine the rotor frequency at no load

Multiple Choice Select 1 out of 4 options for the question below 10 V potential difference is applied across a resistor of 2 kQ The current through the resistor is Options 5A 50 A 5 mA

A conical shaped wire of uniform resistivity has ratio of radius of end cross section 1 3 Resistance of wire is 80 Section PQ divides the wire into two equal halves Choose the correct option s 1 i 2 P ii Question Type Multiple Correct Type 9V Resistance of first half is 60 Resistance of second half is 30 Potential at DO is 2 25V

A conductor with rectangular cross section having dimensions 2a x 4a x 5a as shown in figure If the resistance across AB is R across CD is R and across EF is R3 then the ratio R R R3 is A F U 4a D E 5a 2a B

A meter bridge is in its balanced state The meter bridge wire has a resistance 0 1 ohm cm The current drawn from the battery of negligible resistance is 1 5 amp X ww 40 cm tr 5V 652 60 cm 2 0 1 amp

1 t 5 14 A periodic voltage V varies with time t as shown in the figure 5 249 T is the time period The RMS value of the voltage for one cycle is A Vo 8 VA Vo T 4 T Figure 5 249 B Vo 2 Vo

Design a low pass filter with the following specifications A corner frequency of fc 100 Hz For an input of V 1 V the output should be V 3 V Calculate the time constant of the filter Vi C Vo

A 3 phase 50 Hz 132 kV overhead line has conductors placed in a horizonta plane 4 m apart Conductor diameter is 2 cm If the line length is 100 km calculate the charging current per phase assuming complete transposition

Which of the following is the unit of inductive reactance Ohm Ohm sec Q s min s Ohm sec Q s

In the figure R R 10 19 02 and the ideal battery has emf 12 10 V a What value of R3 maximizes the rate at which the battery supplies energy and b what is that maximum rate a Number Units R E Rs

In a series LCR circuit L 10 H C 160 F and R 80 Q The value of angular frequencies for which the power is half of its maximum value are nearly 46 rad s and 50 rad s 21 rad s and 29 rad s 26 rad s and 34 rad s 26 rad s and 30 rad s

W r t LC oscillation the force constant Kin mechanical system is analogous to which quantity in electric system Reciprocal of capacitance O Inductance min s O Current

Eleven resistors connected in network as shown in figure The equivalent resistance between A and B is B 1 20 2 302 3 19 4 50 Med 25 2 602 www 25 2 402 20 25 20 A1 www www 250 25 60 30

Heat is flowing steadily from A to B Temperature T at point P at distance x from A is such that A P A B C D X T decreases linearly with x T increases linearly with x B T decreases exponentially with x T increases with x as T x

In a potentiometer experiment when terminals of cell are connected at distance of 72 cm on the wire then no current flow through it When 10 Q shunt resistance is connected across cell the balancing length is 50 cm The internal resistance of the cell in is

In potentiometer two cells are connected in such a way that the first time they support each other and second time they oppose each other They are balanced on the potentiometer wire over a 80 cm and 50 cm length respectively compair emf of the cells

3 A battery of 3 0 V is connected to a resistor dissipating 0 5 W of power If the terminal voltage of the battery is 2 5 V the power dissipated within the internal resistance is A 0 125 W B 0 50 W C 0 10 W D 0 072 W

0 A cell of emf 1 5 V having a finite internal resistance is connected to a load resistance of 202 For maximum power transfer the internal resistance of the cell should be a 42 b 0 5 2 c 22 d None of these

9 Assertion Electric appliances with metallic body e g heaters presses etc have three pin connections whereas an electric bulb has a two pin connection Reason Three pin connections reduce heating of connecting cables a Both assertion and reason are true and reason is the correct explanation of the assertion b Both assertion and reason are true but reason is not the correct explanation of the assertion c Assertion is true but reason is false d Both assertion and reason are false AIIMS

Calculate total current in the circuit by applying kirchhoff s voltage law 45 V 2 1 R m 5 KQ 7 5 KQ MA 10 kQ 3 F 4

36 Apply Thevenin s theorem to calculate the current flowing through the 30 22 resistor connected across terminals AB in the network shown 1592 www 150 V 60 52 ww 13 A www 40 92 30 52 ww B

Q2 a Why digital multimeters are preferred over the conventional analog multimeters for testing an electronics circuit How a multimeter is used both as an ammeter and a voltmeter Explain with suitable example for each Explain basic block diagram of multimeter