Current Electricity Questions and Answers

Charge q and q are placed at points A and B respectively which are a distance 2L apart C is the mid point between A and B The work done in moving a charge along the semicircle CRD is A B C 99 4 L 99 2TEL q9 6REL D C 99 6TEL R B D

6 The effective resistance between points A and Bis a R A b R3 R wwwww C 2R 24 2R wwwwww c 2R 3 B d 3R 5

Consider the circuit shown in the figure Given E 5 Volts and R 1 22 Take Vo 0 volt P Q S Codes A B C S 2 3 4 3 2 1 1 2 List I Current through OA in amperes Current through AB in amperes Potential at A in volts Potential at B in volts P Q R 1 4 4 A 4 R www H R www G R www 2E www b R E R B R www R www 2E www 249 R ww 2E www F R www R 2E www www R 1 2 234 3 R 4 C www www R D R E List II 78 1 2

An electric cable of copper has just one wire of radius 9 mm Its resistance is 5 ohm This single copp of cable is replaced by 6 different well insulated copper wire each of radius 3 mm The total resistane 13 cable will now be equal to B 9092 C 7 592 D 27092 A 450 6 A uniform wire of resistance 20 ohm having resistance 152 m is bent int the form of a circle as shown in 19 If the equilvalent resistance between M and N is 1 892 then the length of the shorter section is 5 M N 104 A 2m B 5m C 1 8m D 18m Resistivity of a conductor in which a current density 2 5 Am2 is found to exist when an electric field is applied to it is pq 10 A 60m B 72m EC 40m A D 80m

A wire of resistance 0 1 22cm 1 is bent to form a square ABCD of side 10 cm A similar wire is connected between the corners B and D to form the diagonal BD If a 2V battery of negligible internal resistance is connected across A and C then the total power dissipated is 1 2 W 3 4 W 2 3 W 4 5 W

IBC IDC IDD IBB IAD IA B 1 2 A A D Example 155 Twelve wires each having a resistance of r re connected to form a skeleton cube find the resistance of he cube between the two corners of the same edge Solution Let a current x 2y enter the junction A of the cube ABCDEFGH From the symmetry of the

Which switch in the circuit Fig 4 88 when closed will produce short circuiting a A c C A B b B d none of the above Lamp Resistance

I In the given circuit the potential of the point E is a zero b 8 V c d 3 V A B 8 V Ewwww 10 www 592 WD H form of a circle Th

in the network shown in given figure find the current I through the 10 V battery A B 10 V 1 22 wwwww HA 52 wwwww 1 D 3Q www E F

4 In the diagram given alongside the potential difference across PR is 14 volts Calculate a the equivalent resistance of the network QR b the current flowing through PQ c the potential difference across PQ d the current flowing through the 3 ohms resistor P 52 Q 392 R 602 Ans a 22 b 2 A c 10 V d 1 33 A

A group of N cells each of whose emf varies directly with the internal resistance as per the equation E 1 5 r are connected as shown in the figure The current in the circuit is 1 5 1 A N r Ta 3 2 0 51 A 01015 A

49 The effective resistance between A and B in the network shown is 73 A 30 9 1 34 22 3 17 Q 90 92 40 B ww 30 Q 30 2 2 30 9 4 10 Q

D Twelve equal resistances each of 2 2 form the edges of a cube If a 2 volt battery having internal resistance 0 12 is connected between two adjacement corners of a cube then the current in ampere drawn from battery is a 60 53 b 30 19 c 20 29 d None of the above

but from N to P whereas through R it flows from P to N rough the e The electrolyte through which a current flows has resistance r called the internal resistance Consider situation when

4 A resistance wire connected in the left gap of a metre bridge balances a 10 resistance in the right gap at a point which divides the bridge wire in the ratio 3 2 If the length of the resistance wire is 1 5 m then the length of 1 of the resistance wire is 1 5 10 m 1 5 10 m 1 0 10 2 m 10x10 1 m 1 2 3 1 5 0 g

16 A circuit element is placed in a closed box At time t 0 a constant current generator supplying a current of 1 A is connected across the box Potential difference across the box varies according to graph shown in the figure The element in the box is V volt 292 19X9 8 24 a a resistance of 202 b a battery of emf 6 V c an inductance of 2 H d a capacitance of 0 5 F t s

he galvanometer in the circuit of figure reads zero calculate the value of the resistor R in ko assuming that the 12 V source has negligible internal resistance Pesonance 6 12 V 10 k Wire wound IRI Cell 2V Corporate Office CG Tower A 46 52 IPIA Near City Mall Jhalawar Road Kota Raj 324005 Website www resonance ac in E mail contact resonance ac in ADVCE 60

2 A nichrome wire 1 m long and 1 mm in cross section area draws 4 ampere at 2 volt The resistivity of nichrome is a 1 x 10 722 m c 4 1072 m b 2 10 2 m d 5 x 107 22 m AFMC

24 The effective resistance be for the following network is 492 P A 1 12 392 S C 122 www R ww 69 www 39 B 21 D 21 www S 592 Q Space for Rough V

26 The power dissipated in 3n resistance in the 26 following circuit is R 4 5 V 1Q A 0 75 W C 1 W 202 3Q 60 RED P IR 452 B 0 25 W D 0 5 W Question Id 26 www Faworz 4 5 V 19 2 A 0 75 W C 1 W

E R www 3R www ww 4R 2R ww I Given R 1 kn E 12V 1 1 9 mA 2 2 9 mA 1 19 mA 2E

6 023 x 1023 g mol Find the total negative or positive charge on a 2 g silver coin The atomic number and atomic mass of silver is 47 and 107 9 respectively Given Avogadro s number is 6 023 x 1023 g mol nitive charges in 500 cc of water Given statcoulomb Dista dynes A charge u proportionality equal to 1 So th

dielectric of dielectric constant 3 energy stored in the capacitors to the final total energy stored is 5 In the given circuit the potential difference across the 6 F capacitor in steady state is A E 12V 1 5Q www 19 1 5 Q SHF 165 1 59 O 1 5Q 2 F 1 5 Q H 3 F 6 F B 4V D F 21

In an experiment to verify Ohm s law a graph has been obtained between voltage and current as shown below The resistance is V volt 1 0 0 5 0 5 1 0 1 0 58 0 08 2 10 65 0 0810 Ti A 2 0 3 0 2 0 58 0 12 4 0 58 004 0

Moving Charges and Ma A long straight conductor is bent in form of a right angle as show p q where p 0 q 0 is Moi p q 4 1 1 pq p q 2 Hoi H p q p q 4 q y axis O x axis 2 4 4 1 M p q r Moi 4 q 1 pq p q 2 2 p q p q 2 at poir

In the circuits shown below the readings of the voltmeters and the ammeters will be 10 12 www HH 10 V Circuit 1 a V V and i 1 b V V and i 1 c V V and i i 10 12 www 1092 10 V Circuit 2

78 Find the reading of ammeter in figure 2 3 A b 4 A c 1 5 A d 6 A Parratell 222 ww 202 ww HH 3 V 5 F 11 A

25 In the given circuit all resistors are of R ohm each If a wire is connected between C and B then the ratio of equivalent resistance between AB of original circuit to new circuit formed is Ao 1 1 1 RCRD R www Po 2 3 1 R E 3 1 3 R www ob

Terence between points x and y in the circuit shown below is A 1 10 volt 3 30 volt 50 2 X www 50 22 www 30 Q y M 10 2 HE 80 volt Ux vy VB 2 20 volt 4 40 volt

Resistance R in the circuit has to be chosen such that maximum power consumed across it in that case the Power consumed by R A 1 W 10V M 20 302 B SW C 10 W D 20 W

Calculate equivalent resistance between the points A and B if A B 202 6 www 22 4 Q www tim www 4 52 422

What should be the bill for the month of March for a heater of resistance 60 5 2 connected 220 V mains The cost of energy is Rs 2 per kW h and the heater is used for 3 hours daily

Q 49 In the circuit shown in the figure the neon lamp lights up if potential difference across it becomes 60 V and goes out if the potential difference falls below 30 V The inductor coil has a very small resistance and emf of the cell is V 4 volt The lamp does not light when the switch is closed The neon light flashes once when the switch is opened Explain why www Coil ooooo

25 Which of the following equations is Kirchhoff s first rule as applied to the circuit given below 6 V 2 6 V 02A 13 M 209 12 20 9 20 2 9 1 1 13 0 3 1 12 13 0 26 Which of the following is not a correct equation by Kirchhoff s second law for the above circuit 1 6 201 6 20 2 0 3 20 2 6 20 3 0 27 What is the value of I in the above circuit 1 0 1 A 2 1 12 13 0 4 1 1 13 0 2 6 2013 201 0 4 6 2013 201 0 2 0 1 A 4 0 2 A 25

04 X material of the ong Answer Type Question 24 a Define resistivity Write an expression for the resistivity of a substance Give the meaning of each symbol which occurs in it b State the SI unit of resistivity c Distinguish between resistance and resistivity d Name two factors on which the resistivity of a substance depends and two factors on which it does n embentou 4t didn e The resistance of a metal wire of length 1 m is 26 92 at 20 C If the diameter of the wire is 0 3 mm w will be the resistivity of the metal at that temperature

39 If power consumptions in R R R3 are the same then what will be the relation between them ww R 1 R R R3 2 R R3 2R 3 R R3 4R 4 R R 4R R R

ces the thermoco an e m f of 40 V C in the linear range of temperature A galvanometer of resistance 10 ohm whose sensitivity is 1 V div is employed with the thermocouple The smallest value of temperature difference that can be detected by the system will be 1 0 25 3 A A 2 0 5 C 410 1 C 23

R C uus 16 At t 0 charge on capacitor is q Now switch S is closed Heat loss in 3R is x x 10 J Then find the value of x Given q 15 C C 6 55 F 971 R 2R ww shxt 0 2 of gire resistor not capacitor in 1 R R

In the circuit PR the reading of the galvanometer is same with switch S open or closed Then A IR IG B Ip IG C lg IG D IQ IR 19

8 A charge Q is placed at each of the two opposite corners of a square A charge q is placed at each of the other two corners If the resultant force on Q is zero then a Q 2q c Q 2 2q b Q 2q d Q 2 2q

In the figure the numerical values denote 4 resistances in SI units The total resistance of the circuit between a b will be ww 1 12 ohms 3 15 ohms www 3 ww 20 wwww 15 ww 20 www ww 16 30 b 2 24 ohms 4 6 6hms 50

3 Resistances of b manner shown in adjoining figure With the current 0 5 ampere as shown in figure the potential difference Vp Vo is P 0 5 A 692 wwww A V C V 3 60 www 60 N A 3 6 V C 3 0 V The potential difference B in figure will be 502 592 ww wwwwww A 502 652 692 wwwww 652 wwwww B 6 0 V D 7 2 V between the points A and 592 2V ve 552 B 502 B V a D 2V

1 The dimensionally correct expression for resistance R among the following is P electric power electric current t tim V voltage and E electric energy 1 R PI OBEYGR 2 R E 1 t

133 Which of the following graph represents the variation of resistivity p with temperature T for copper 1 P 2 P 3 P 4 P 2 T T T TS 12 27 1227X1 lood 12 27x1 107

Figure shows part of a circuit Calculate the power dissipated in 3 2 resistance What is the potential difference Vc VB C 192 12 V 5 A D 29 322 3 V E 422 2A 6 A 622 B

In the given circuit reading of ideal voltmeter is A 2 V B 4 V C 6 V D 8 V 8 V ww 20 40 20 40 20

106 In given figure the potentiometer wire AB has a resistance of 5 2 and length 10 m The balancing length AM for the emf of 0 4 V is a 0 4 m A 5 V 11 0 4 V R 4592 ww O M b 4 m B

ors of 65 Equivalent resistance of the network between points A and B is 2 are arranged in a square as shown A M E LLOR So 3

At what value of resistance x in the circuit shown will the total resistance between points A and B be independent of the number of cells A R www www www w 2R 1 R 3 1 R www 2R 2R R www R www www 2R 2 R www X

8 The variation of terminal potential difference V with current flowing through a cell is as shown 3 V V in Volt cell are 6 A 1 in A The emf and internal resistance of the Vr Tr