Current Electricity Questions and Answers

The resistnace of a wire of length 2m and area of cross section 0 5 mm is 2 20 The specific resistance of the material of wire will be Question Type Single Correct Type 1 5 5 x 10 70 m 2 Zero 3 5 5 107 Q m

Q 2 Two resistors are connected in series gives an equivalent resistance of 100 When connected in parallel gives 2 4 2 Then the individual resistance are a Each of 5 Q b 6 2 and 4 Q c 702 and 4 Q d 8 Q and 2 Q

For the circuit shown A C Current across AC is 0 98A Current across DB is 2 41A 1 2 602 2 1 C 71002 D 49V 202 B D wy 70 L 1 2 Y Current across CD is 0 34A Current across AD is 2 75A 55

E E 1 R R R 9 3 zero 2 E R www Current through the battery immediately after key K is closed and after a long time interval R ww www R 12 4 B E 2 R R D 2 R E R R E R R 2 R R3 E R

For the circuit shown in the diagram find the value of V V just after closing the switch S 152 www 252 www 1 4 V 2 8 V 352 www H 24V b a 35 www S 3 12 V 4 16 V RPMT 2010

Draw a graph of conductivity vs temperature for a metal a semiconductor and a superconductor O The resistance R experienced by an electrical wire of pure copper can be ad using the formula below

Between the plates of parallel plate condenser a plate of thickness t and dielectric constant K is placed In the rest of the space there is another plate of thickness t and dielectric constant k The potential difference across the condenser will be o 5 A k k Q 3 A k k A t 2 4 QL A EQ k t k t

In the circuit given charge in uC on each capacitor in steady state will be 452 2 19 3 F HI 3 F 452 402 ww Fww 10V 12 3 8 3 F 11 3 F 4 6

14 In the circuit all bulbs consume same power resistance of bulb 1 is 36 2 then resistance of bu 3 and 4 are BA 1 42 122 3 92 49 B 002 B 00 4 B m 00 2 422 92 4 99 90 Topic Cells i Choose 1 Av Com diam the

In a metre bridge experiment null point is obtained at 20 cm from one end of the wire when resistance X is balanced against another resistance Y If X Y then where will be the new position of the null point from the same end if one decides to balance a resistance of 4X against Y Question Type Single Correct Type 1 50 cm 2 80 cm 3 40 cm 4 70 cm

An electron moves on a straight line path XY as shown The abcd is a coil adjacent to the path of electron What will be the direction of current if any induced in the coil Question Type Single Correct Type 1 No current induced 2 abcd 3 adcb a electron d Y

um logic gate we switch cloxo I uhim ourdon t wined Path 6V 221 1 bez it will offer existence m 14 The circuit 1 NOR 3 OR A 0 B 71 31 ww R ww R LED Y 2 AND 4 NAND

66 A capacitor of 8 F is connected as shown Charge on the plates of the capacitor a 32 C b 40 C c OC d 80 C 2014 8 F 5 V 20 22 422 12 Karnataka CET

A universal motor ac operated has a 2 pole armature with 960 conductors At a certain load the motor speed is 5000 rpm and the armature current is 4 6 A the armature terminal voltage and input are respectively 100 V and 300 W Compute the following assuming an armature resistance of 3 5 2 a Effective armature reactance b Maximum value of useful flux pole

In the LC circuit at this time Q Q 00000 1 is increasing and Q is increasing 2 is increasing and Q is decreasing 3 is decreasing and Q is increasing and deprem

figure the circuit is switched on and the variable resistance is adjusted such that the bulb just glows Now if the circuit is switched off www Answer A Your Attempt Rate this question Correct answer the bulb stops glowing

2 The drift velocity of the free electrons in a conducting wire carrying a current I is v Consider a wire of the same metal but of double the ra dius and carrying a current 21 The drift velocity of the electrons for the second wire will be a v 4 b v 2 c v d 4y

0 2 mA oltage is fed to the amplifier with common emitter configuration as given by the equati Vin Vo sin 145t where t is time The output voltage from the amplifier may be Vin Vosin 1957 1 Vout Vo sin 145t 7 3 Vout Vo sin 145t 6 2 Vout Vo sin 145t x T 4 Vout Vo sin 145t

or j oE where o 1 p is called the conductivity Ohm s law is often stated in an equivalent form Eq 3 13 in addition to Eq 3 3 In the next section we will try to understand the origin of the Ohm s law as arising from the characteristics of the drift of electrons

For a sensitive potentiometer a the wire must be of small length b the external potential difference should be large c the wire must be of larger length d external potential difference should be small 1 Point Option a Option b Option c Option d

Question 26 M M 4 00 Switch S is closed at t 0 to begin charging of uncharged capacitor of capacitance C 15 F through a resistance C R 2002 The time after which potential difference across the capacitor is equal to that across the resistor is given by a ln 2 milli second Then write down the value of in OMR sheet 10 X N M 0 00 www R

Secondary output of a transformer is 12 V for 220 V primary input Which of the followin statements is true for this transformer a It is a step up transformer with turns ratio greater than 1 b It is a step up transformer with turns ratio less than 1 c It is a step down transformer with turns ratio less than 1 d It is a step down transformer with turns ratio greater than 1 8 2

attempted questions will be con ned for marking A current carrying wire AB of length 2nR is turned along a circular arc as shown Then magnetic field at O A B B It 0 Hoi 2 0 Correct Answer My Answer

8 Radii of conductors 1 2 as shown below are r 2r If the resistivity of their materials are same and equal to p then current drawn from the battery will be 2 4 r E 3 1 E 58 27 2 1 E

Given a current carrying wire of non uniform cross section Which of the following is constant through out the wire a O Current and drift speed b O C Drift speed only O Current only

c 3 Volt d 4 2 Volt 35 A current of 6A enters one corner P of an equilateral triangle PQR having 3 wires of resistances 20 each and leaves by the corner R Then the current I and 1 are KCET 2006 6A a 244A b 4A2A c 14 2A d 24 3A Q 292 A current 2 A flows through a 202 resistor when connected across a battery The same battery supplies a current 05 A 292 I WWW P 12 WW 202 R 41 a 2 A c 1 A A battery resistance current I R alone best desc a I ap b I ap c I ap

The circuit diagram shows a source of emf 10 V having an internal resistance of 2 50 connected to an ideal ammeter The jockey can be slided to different points on the Rheostat whose total resistance is 102 What can be the reading of the www DIA 2A jockey A wwwwwwww B

Four capacitors are joined as shown in the figure The capacity of each capacitor is 8uF Equivalent capacitance between A and B is A 1 2 F 3 16 F H1 2 TH B 8 F An P

8 A circuit consists of five identical conductors as shown in figure The two similar conductors are added as indicated by the dotted lines The ratio of resistances before and after addition will be a c 755553 12 12 1Q 12 b d 315 65 19

48 A circuit consists of five identical conductors as shown in figure The two similar conductors are added as indicated by the dotted lines The ratio of resistances before and after addition will be a G 5 192 12 192 19 b d 315 615 12

3 4 C 17 Consider the combination of resistors as shown in figure and pick out the correct statement R wwww R A www R6 wwwwww R R www www R5 1 R R are connected in parallel 2 R R are connected in series 3 R R are connected in parallel B

In a wire of cross section radius r free electrons travel with drift velocity v when a currentflows through the wire What is the current in another wire of half the radius and of the same material when the drift velocity is 2v Question Type Single Correct Type 1 21 21 3 1 2

In the balanced condition the values of the resistances of the four arms of a Wheatstone bridge are shown in the figure below The resistance R3 has temperature coefficient 0 0004 C 1 If the temperature of R is increased by 100 C the voltage developed between S and T will be volt R 600 R 300 0 50 V V R R 1000 500 0

0 Consider a rectangular slab of length L and area of cross section A A current I is passed through it If the length is doubled the potential drop across the end faces a becomes half of the initial value b becomes one fourth of the initial value c becomes double the initial value d remains same J K CET

Two electric bulbs whose resistances are in the ratio of 1 2 are connected in parallel to a constant voltage source The powers dissipated in them have the ratio 11 2 2 1 3 21 4 1 4

In the circuit shown the current in the 192 resistor is 6V 3 0 a 0 13 A from Q to P c 1 3A from P to Q P 202 W 102 9V 2 30 b 0 13 A from P to Q 0 08

A material B has twice the specific resistance of A A circular wire made of B has twice the diameter of a wire made of A then for the two wires to have the same resistance the ratic B A of their respective lengths must be B A a 1 c 4 b 1 1 1 2 d 2

When 5V potential difference is applied across a wire of length 0 1 m the drift speed of electrons is 2 5 10 4 ms If the electron density in the wire is 8 1028 m 3 the resistivity of the material is close to a 1 6 10 6 m c 1 6 10 8 Om b 1 6 10 5 m 16x10 70m

A thermocouple is made from two metals Antimony and Bismuth If one junction of the couple is kept hot and the other is kept cold then an electric current will a flow from Antimony to Bismuth at the hot junction b flow from Bismuth to Antimony at the cold junction c now flow through the thermocouple d flow from Antimony to Bismuth at the cold junction

The equivalent resistance between point A and B is RAR R BR a R b R 4 c 4R d 2R 3

Four ideal cells each of emf 10 V are connected as shown in figure The current through 2 Q2 resistor is 1 2 A 2 4 A 3 1 A 10V 10V www 2Q2 89 10V 10V

1 20 Mark for Review The effect of eddy current loss in transformer is reduced by O Using laminated core Using thick wire for winding Using solid non laminated core 18 59 min se Using thin wire for winding

The circuit below represents a non inverting integrator For high frequencies o the input impedance is a 0 b R For low frequencies o the input impedance is c R 1 ORC d a V 1 RC V di b The voltages at the inverting and non inverting terminals of the op amp are nearly c The voltage at the non inverting terminal of the op amp and the current in the resistor attache are 2 out of phase 2 d The current in the two resistors are in phase

A ring composed of three sections The cross sectional area is 0 001 m for each section The mean arc length are Ia 0 3m Ib 0 2m Ic 0 1m An air gap length of 0 1 mm is cut in the ring ur for sections a b c are 5000 1000 and 10000 respectively Flux in the air gap is 7 5 10 WB Find 1 MMF 2 Exciting current if the coil has 100 turns 3 Reluctance of the sections

A non conducting ring of radius R and mass m having uniform charge distribution having a small cut of length b b R is released from rest with its plane parallel to uniform electric field of strength E as shown in the figure If the maximum angular then find the value of C Neglect gravity velocity of the ring is CqEb 22mR R E 90

a Obtain the equivalent circuit of a 200 400 V 50 Hz single phase transformer from the following test data O C test 200V 0 7A 70 W on L V side S C test 15V 10A 85W on H V side Calculate the secondary voltage when delivering 5kW at 0 8 pf lagging the primary voltage being 200V

Consider a series RC circuit as in the figure below for which 0 00 MQ C 9 00 u and 8 21 0 V a Find the time constant of the circuit b What is the maximum charge on the capacitor after the switch is thrown closed Inc c Find the current in the resistor 10 0 s after the switch is closed PA

5 Current sensitivity of a moving coil galvanometer is 5 div mA and its voltage sensitivity angular deflection per unit voltage applied is 20 div V The resistance of the galvanometer is 2 2522

In the given circuit current through the zener diode is 30 mA 24 mA 36 mA 9V V 6V wwwww 10002 wwww 1k02

4 Cannot be calculated unless value of C is not given 4 In an L R circuit AC source of frequency 50 Hz is connected as shown in the figure The phase differenc between voltage and current is www R 157Q L 1 H 2 3 momo