Current Electricity Questions and Answers

bridge experiment the null point obtained at N The value of unknown resistance will be 1 60 S R 102 X www 40 cm N E K 2 40 Q

12 V 1 2 1 A m R Figure 3 9 Given the circuit in Figure 3 9 what resistance is required to draw the specified current 11 40 5 7 k 25 20 5 70

A circuit shown in figure has resistance R and R At what value of the resistance Rx will the therma power generated in it be practically independent of small variations of that resistance The voltage between the points A and B is supposed to be constant in this case take R 9 R 3 B R Your Answer Unattempted Correct Answer R www Rx Rate this ques

4 Angular momentum 33 Two pith balls having charge 3q and 2q are placed at distance of a from each other For what value of charge transferred from 1 ball to 2nd ball force between balls becomes maximum 1 JIN N 2 5q 3 7q 4 q slast Leader Achiever ALL PHASE 4 u a current affa e a fan anda serata fan and auf 3 1 2 1 2 TIN 5q 2 3 7q 4 q 2 1001CMD3031191

In the circuit given here the points A B and C are 70 V zero and 10 V respectively Then B 1092 A WW D www www 2002 300 C 1 The point D will be a potential of 60 V 2 The point D will be a potential of 20 V 3 Currents in the paths AD DB and DC are in the ratio 1 2 3 4 Currents in the paths AD DB and DC are

When no current is passed through a conductor 1 The free electrons do not move 2 The average speed of a free electron over a large period of time is zero 3 The average velocity of a free electron over a large period of time is zero 4 The average of square of velocities of all the free electrons at an instant is zero

The intensity of the electric field required to keep a water drop of radius 10 cm just suspended in air when charged with one electron is approximately 1 260 V cm 2 260 N C 3 130 V cm 4 130 N C

A cell of emf E and internal resistance r is connected across a variable external resistance R a Plot a graph showing variation of E with R b Plot a graph showing variation of Terminal potential difference V with R c When will the current through the circuit becomes maximum

The current delivered by battery in the following circuit at steady state condition is diode and inductor are ideal 1 R 3 T www R ww 2 eeeee 2 R

An electrical device is designed to operate from 240 volt line to obtain the 960 watt of power that it needs The available power supply is 120 V line therefore a step up transformer is used whose primary winding and secondary winding have N turns and N turns respectively so that the electrical device works at its optimum power A 120 V B Power Supports Step up Transform Electrical Device A The resistance of electrical device is 60 ohm C The current in primary winding is 8 amp B The resistance of electrical device is 30 ohm D The current in primary winding is 4 amp

A potentiometer wire has length 8 m and resistance 16 2 The resistance that must be connected in series with the wire and an accumulator of emf 4 V so as to get a potential gradient of 1 mV per cm on the wire is 1 48 2 16 3 32 4 64

1012 Current Electricity 3 For the circuit shown the charge on the capacitor will be MP PMT 20 UNIVERSAL BOOK DEPOT 1960 a CE CER C HH E R www R www b CER R r CER

Negative Marks 1 In all other cases In the circuit shown find the value of current I A 4 amp B 2 amp 20V Hly 552 20 ZV H 2V HH 20V HE 10V C 1 amp D zero

A storage battery of emf 8 0 V and internal resistance 0 52 is being charged by a 120 V dc supply using a series resistor of 15 5 22 What is the terminal voltage of the battery during charging What is the purpose of having a series resistor in the charging circuit In a potentiometer arrang 11 nant

22 20 wire is connected between points A and B then the current in the wire AB will 15V 192 www J2V 3 x 1 0 2 452 ww 1216 Aw I 292 B 292 www If V 2 volts Both V K 1 be from A to B 2 be from B to A have 3 Not flow 2 Veach but 4 Direction of current will be decided t

2 Page view A Read aloud Draw A battery has emf E a x where a and are constant and is connected as shown to a potentiometer If initially x 0 then which of the following is are correct TYM V Vee Man Advanced A x x HH www key 1 Variation of x with AP where P is null point is linear 2 For x x constant there is only one value of where null point is obtained 3 IF

Two cells of same emf E but internal resistance r and rare connected in series to an external resistor R Fig 3 7 What should be the value of R so that the potential difference across the terminals of the first cell becomes zero E ww R E it Big 3 7 B

There are m rows of cells each with n identical cells connected in series Each cell has an internal resistancer The combination is connected to an external resistance R What is the condition for maximum current through the external resistance a R nr b R mr C nr m

the correct statement 0 1 Point A capacitor can conduct a dc circuit but not an inductor In a dc circuit the inductor can conduct but not a capacitor In dc circuit both the inductor and capacitor cannot conduct The inductor has infinite resistance in a dc circuit

e are two small uncharged spheres placed at a distance of 1 m from each other N number of electrons are transferred from one sphere to her The force between the spheres is now measured to be equal to 2 newton then the value of Nis 4 8 x 105 O 61 x 102 O 28 x 106 O 93 1013

The circuit shown consists of two resistances of values R and 3R two identical capacitors each of capacitances C two identical inductors each of inductance L and ideal battery of electromotive force and a switch Initially the switch was closed for a long time and the circuit was in the steady state then the switch is opened Voltmeter is ideal zey qkqy ma Ra 3R fa u ukm c H u sa Dichcd L TH g ta au faya mgc d e ef az 1 m 4 Ma ar gou fay d 6 am qkqy ze gaze duy ka n um 3ntef A z 3R ooooo D E www ellee In steady state voltmeter reading was a cchiez che quiche w az Correct Answer B the voltmeter reading becomes 2 Rda at utat gerd 816 dcc ice che ich 2e Immediately after the switch is opened Correct Answer Immediately after the switch is opened the voltmeter reading becomes Raat ulat ge d DG B rchicz h udih e s In steady state voltmeter reading was 2 aze dechizz chi qoich 2

A weight is hung over a pulley and attached to a string composed of two parts each made of the same material but one having four times the diameter of the other The string is plucked so that a pulse moves along it moving at speed v1 in the thick part and at speed v in the thin part What is v v 2 V2

For the network of resistance shown in the hg the equivalent resistance of the network between the points A and B is 180 The value of unknown resistance Ris B WW 1 80 1002 R www 102 www 1002 2 10 2 100 01002 www 3 16 2 O A Pre Medical 43 Resistors R and R have an 4 24 Q CE0040 below The resistance of 1 1 www 2 5 44 Value of curre

An uncharged capacitor of capacitance C 10 uF and an inductor coil of inductance I 2 mH are connected with two identical resistances R 20 02 each an ideal voltmete and an ideal battery of emf 100 V as shown Initially the switch is open and current is zero everywhere The switch is closed at t 0 If the reading of the voltmeter reaches its maximum value x at r 1 then www L R 20 ww R vooooo E t 2log 2 x10 s MAY 25 V t 410g 2 x10 s VMAX 50 V

In the circuit shown the current through the 4 22 resistor is 1 A when the points P and M are connected to a d c voltage source The potential difference between the points M and N is P 3 1 0 5 volts 422 wwww 0 50 www 302 wwwwww 0 52 Svelts N www 192 2 3 2 volts M

A battery of e m f 2 volts and internal resistance 0 1 is being charged with a current of 5 A Calculate the potential difference between the terminals of the battery 1 1 5V 2 2 5V 3 IV 4 2V

A cell in the secondary circuit gives null deflection for 2 5 m length of a potentiometer having 10 m length of wire If the length of the potentiometer wire is increased by 1 m without changing the cell in the primary the position of the null point will be A 3 5 m YOU B O 3 m

1 1 5 2 2 50 3 6 67 02 4 200 Q In the given circuit the current through the Zener 30 diode is 20V IkQ wwww 12V 2kQ 1 1 mA 2 2 mA 3 6 mA 4 10 mA In the circuit shown in the following figure the 31 1 5V 3 6 67 02 4 far am 1 1 502 2 502 f af Erft 20V IkQ 12V 1 I mA 2 2 mA 3 6 mA 4 Y

Two uncharged identical capacitors A and B each of capacitance C and an inductor of inductance L are arranged as shown in the adjacent figure At t 0 the swi S is closed while switch S remains open At time t to VLC 71 switch S is closed while switch S is opened The charge on capacitor A after time to is CE The current flowing through the inductor at t to is zero E SH S B S

3 Iron box is a heating device a Which substance is used to make heating coil b A 1000W Iron box works at its marked power What amount of heat energy will be rele Iron box in one second c 2A current is flowing through a 100 9 resistor Calculate heat generated in two minute

f percentage change in radius of a conductor is 2 keeping volume constant then percentage change in ohmic resistance will be O 2 O 4 O 6 8

Given that there is a square face cuboid whose length is 10 cm breadth is 5 cm What will be the ohmic resistance between square face if resistivity 50 10 0 m D E 100 050 20 C H G

In the arrangements of four bulbs as shown in figure total power consumption will be 150V 100W 150V 100W B 200 W 350 W 500 W 200V 200W 200V 100W 300V

Figure shows a circuit in steady state power consumed by battery is 30W O charge on capacitor C is 40 C O current in resistor R is 2A R www the www R R www R C 30 V 10 V R R R R 100 C 2uF

A conductor with rectangular cross section has dimensions a x 2a 4a as shown in figure If the resistance across AB is R across CD is R and across EF is R3 then A O R R R3 ED R R R3 C R R3 R 4a F 2a B

a sphere of radius 5 cm has a charge of 31 41 micro coulomb calculate the surface charge density of charge two similar spheres are suspended by strings of equal length when they are suspended in air then the angle between the string is 30 the angle remain same when they are suspended in a liquid of density 0 8gm cm calculate the dielectric constant of the liquid if density of the material of the sphere is 1 6 gm cm

The equivalent resistance between A and B is C 4R 2R R A O Bo wwwwwww R R 2R 2R www 2R www R

A uniform wire of total resistance 21 ohm is bent in shape of an equilateral triangle The value of equivalent resistance between any two vertices of the triangle is 020 67 C Read More 1121228

Choose the correct statements among the followings A An ammeter should have small resistance B An ammeter should have large resistance C A voltmeter should have small resistance D A voltmeter should have large resistance A and C B and D A and D B and C

Two batteries V and V are connected 1 2 to three resistors as shown below If V 2V and V 1 2 I Mw OV the current I V 3 mA If V OV and V 4V the current 1 1 4 mA Now if V 10V and 1 V 10V the current I will be 2

4 In a marriage hall there are 15 bulbs of 45 W 40 15 bulbs of 100 W 15 small fans of 10 W and 2 heaters of 1 kW If the voltage of the electric main is 220 V then the minimum fuse capacity in A of the building should be 1 20 A 2 15 A 3 10 A 4 25 A 45 W 15 100 W 151kW 15 10 W 2 2 1 af faga A B affe 1 20 A 3 10 A 2 15 A 4 25 A 220 V Aff

1 A parallel combination of following cells is connected to an external load If all the cells are connected in same polarity then the value of resistance of the external load such that the power transfer to the load is maximum is S No EMF Internal Resistance 2 This section contains 15 SINGLE CORRECT TYPE questions Out of these 15 questions candidate can choose to attempt any 10 3 4V 40 6 V 40 Phy Section B 2 V 20 030 020 Read More

1 60 V 2 30 V 3 20 V 4 40 V A battery of internal resistance 40 is connected 38 to the network of the resistance as shown in the figure To deliver maximum power to the network the magnitude of resistance R in X should be 21 1 19 4R Find x 2R m 6R 2 17 R E 40 4R 3 19 2R 4 23 del 6 1 60 V 2 30 V farger et far far 1 19 X 4R 4 fa af 2R www 6R 3 20 V 4 40 V 2 17 y R www E 40 www 4R 3 19 X 61 21 2R 4 23

na parallel combination of resistors the equivalent resistance is A Smaller than the smallest one C Greater than the smallest one E Equal or smaller than the smallest one B Equal to the smallest one D Equal or greater than the smaller one

A piece of copper and another of germanium are cooled from room temperature to 80 K The resistance of A each of them increases B each of them decreases C copper increases germanium decreases D copper decreases germanium increases E each of them remains constant

Phy Section B This section contains 15 SINGLE CORRECT TYPF questions Out of these 15 questions Read More Two cells of emf 2 V and 4 V respectively and internal resistance 1 0 each are connected in series with emf in opposite sense The equivalent emf of the combination is O 6 V O 2 V 3 V

A magnet is moved in the direction indicated by an arrow between two coils AB and CD as shown in fig The direction of the induced current in each coil is 1 2 3 A to B in coil X and C to D in coil Y A to B in coil and D to C in coil Y B to A in coil X and C to D in coil Y B to A in coil X and D to C in coil Y 0000000 Y D N S 0000000 X B

4 27 6 1 A ring is made of a wire having a 23 resistance R 12 2 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 circuit 8 between these points is equal to 1 550 11 11 5100 A B 55 55 11 11 12 113 4 27 6 1 e fartu R C a R 12 2 fad at fargit A i B katet e a and arfer saat far oit after 34 ufua 8 52 52 3 11 3 100 5 8 11 22 55 11 113

Incandescent bulbs are designed by keeping in mind that the resistance of their filament increases v increase in temperature If at room temperature 100 W 60 W and 40 W bulbs have filament resistanc R60 and R40 respectively the relation between these resistance is IIT JEE 2010 Pa 1 B R100 R40 R60 1 1 A 100 1 R40 C R100 R60 1 R60 R40 D 108 1 R 00 R60 R40

A galvanometer having a resistance of 20 2 and 30 divisions on both sides has figure of merit 0 005 ampere division The resistance that should be connected in series such that it can be used as a voltmeter upto 15 volt is JEE Main 2019 1 100 2 2 125 2 3 80 2 4 120 9