Current Electricity Questions and Answers

me nt ne of Shown in the fir are for one complete cycle is Vo 1 2V B TU V Sinusoidal lobes D 14 Vo

Two identical cells are connected in a series b parallel then maximum power transfered to the load is 1 Same in both cases 2 Different in both cases 3 May or may not remain same depending upon polarity of the cell connected 4 None

AB is a wire of potentiometer With the increase in the value of resistance R the shift in the balance point J will be E www A H 1 towards B 2 towards A 3 remains constant 4 first towards B then back towards A

Pre 13 The brightness of light bulb when a heating appliance is switched on will 1 decrease for non ideal source but remain same for ideal source 2 Increase for non ideal source but remain same for ideal source 3 Remain same for both ideal and non ideal source 4 Remain same for non ideal source but decrease for ideal source

5 In a potentiometer the null point is received at 7th wire If now we have to change the null point at the 9th wire what should we do 1 Attach resistance in series with cell of secondary circuit 2 Increase resistance in main circuit 3 Decrease resistance in main circuit 4 Decrease applied emf

A bistable multivibrator with a saturation voltage 5V is shown in the diagram The positive and negative threshold at the inverting terminal for which the multivibrator will switch to the other state are a 5 11V 0 01 F b 10 11 2MQ 2MQ 200k to c SV d 11V

Two cells of unequal emf E and E having 2 internal resistance r and r are connected as shown in figure E r E 1 Potential difference across any of the cell cannot be zero 2 Potential difference across cell of smaller EMF may be zero 3 Potential difference across cell of larger EMF may be zero 4 Potential difference can be zero only if EMF of both cell are same at 371 1

4 A particle of mass m and charge q approaches from a very large distance towards a uniformly charged ring of radius R and charge mass same as that of particle with initial velocity Vo along the axis of the ring as shown in the figure 1 420 What is the closest distance of approach between the ring and the particle Assume the space to be gravity free and frictionless 4 q V 2 2 2 4 TEM VO TWITT m 4 q R Smooth Figure 1 420 B Ring T 394 2 2 m v 4 R

Eight connected in the circuit as shown in figure The equivalent resistance between A and B is C A B C A 013 16 2 3 15 7 19 2 wwww www B E www D Correct Answer

4 A resistor of 40 ohms is in series with two resistors A and B in parallel The resistance of A is 100 ohms The entire series parallel circuit is connected acros 120 volt supply Determine the resistance in ohms to which resistor B must be adjusted in order that current to entire circuit to be 1 2 amperes Solution 200 Q 175 Q 125 Q O 150 Q

Two resistances R and R are made of different materials The temperature coefficient of the material of R is a and that of the material of R is B The resistance of the series combination of R and R does not change with temperature then the ratio of resistances of the two wires at 0 C will be 1 3 a B 2 B R 2 a 4 2215 10 1

A rectangular sheet of copper is 2 00 mm thick and has surface dimensions 8 0 cm x 24 cm If th long edges are joined to form a tube 24 cm in length find the resistance of the tube in micro ohm between the ends of the tube Resistivity of copper 1 6 x 10 22 m

For the circuit shown the switch was at a for long time At t 0 the switch is moved to b The solution for the capacitor current variation found to be i t 2 5 e 0 5 mA for 120 Find the values of V 2 and R 5V t 0 1kQ2 www 1mF i R www V 2

11 In a non ohmic conductor electron density varies with electric field as n x E Find how the current varies with applied voltage for this conductor if drift velocity is proprotional to the applied electric field GOIITJEE SALT LAKE 98741956751 BALLYGUNGE GOLPARK 7044094543 goiitjee gmail com I www iitopper com

15 What is the equivalent resistance of the arrangement of resistors shown here 10 Q www www 5 0 2 6 0 2 3 0 2 wwww 2 0 92 wwww 4 0 2 4 0 wwww 5 0 Q 8 0

17 A value of co for which the current amplitude is 17 1 2 power dissipated by the circuit becomes 1 double 3 one third times its maximum value At this value the 2 one fourth 4 half initially charged is connected 18 T 1 3 Uch faels cha YZ

A wave is propagating in a medium of dielectric constant 2 and relative m permeability 50 The wave impedance a medium is 1 5 Q 3 1883 N 2 376 6 S 4 3776 Q the

A milli ammeter of range 10 mA and resistance 9 Q are joined in a circuit as shown in the figure The meter gives full scale deflection when current in the main circuit is I and A and D are used as terminals The value of I is A A B www 0 192 C B 1 09 A 10 9 A zero 0109 A wwww 0 3 C wwww 0 62 D 0 992 E Correct Answer

20 Find the equivalent resistance between A and B if each resistor has a resistance R A m ww m R

An ac millivoltmeter has a range of 0 1000 mV and its accuracy is 0 5 of fsd full scale deflection If the input voltage of the instrument is 400 mV the output of the instrument would be a 402 mV c between 398 and 402 mV b 398 mV d between 395 and 405 mV

A battery of unknown emf connected to a potentiometer has balancing length 560 cm If a resistor resistance 1002 is connected in parallel with the cell the balancing length change by 60 cm If th internal resistance of the cell is 10 O the value of n is

Graph between terminal voltage V V and current flowing through the same cell is shown Current direction from 1 to 2 is taken as positive B Portion AB indicates charging of cell 2 1 Portion BC indicate discharging of cell Neither 1 nor 2 Both 1 2

O A thin uniform wire AB of length 1m an unknown resistance X and a resistance of 12 2 are connected by thick conducting strips as shown in figure A battery and a galvanometer with a sliding jockey connected to it are also available Connections are to be made to measure the unknown resistance X using the principle of Wheatstone bridge After appropriate connections are made it is found that no deflection takes place in the galvanometer when the sliding jockey touches the wire at a distance of 60 cm from A Obtain the value of resistance X A X www un C B

I have written the standard equation of a straight line for this sum upto y mx 2 c But what to do next 105 In an experiment the resistance of a material is plotted as a function of temperature in some range As shown in the figure it is a straight line In R T One may conclude that T2 T c R T Roe T T ele a R T Roe 1 72 JEE Main 2019 T T2 b R T Roe T T2 d R T Roe

two electric bulbs of the same power but with different marked voltages are connected in series across a power line Their brightness will be O 1 directly proportional to their marked voltages 2 inversely proportional to their marked voltages 3 directly proportional to the squares of their marked voltages 34 4 inversely proportional to the squares of their marked voltages

A galvanometer has a resistance 5k2 and shows a maximum deflection when a current 20mA flow through it How will you convert this galvanometer into i an ammeter reading up to 10 A current ii a voltmeter reading up to 250 V

the charge density in the beam if the total current is 2 10 A The mobility of electrons in a conductor is defined by the equation vdrift E Find an expression for in terms of conductivity of an Ohmic conductor 1 In a non ohmic conductor electron density varies with electric field as n x E Find how the current

The resistance of an average adult human body is 300 2 Find the charge that will flow through a man s body in 5 seconds if he touches a 220V wire with his hand when his feet are touching the ground

What is expected when 20 kn 1 W resistor in parallel are used instead of 1 10K 1 W O a Provides less power O b Provides higher current O c Provides more power O d Provides more tolerance

A battery of emf 10 V and internal resistance of 30 is connected to a resistor The current in circuit is 0 5 A What is terminal voltage of battery 2 6 V O 9 5 V 7 5 V 8 5 V

A certain resistance was measured to be 30 2 at 20 C and 40 Q at 5 C Find the temperature coefficient at 0 C and 25 C and the ferred zero resistance temperature Ans Tx 205 C a 0 00488 C 25 0 00435 C

A wire of resistance 9 ohm is broken into two parts The ratio of cut length 1 These two pieces are connected in parallel The net resistance will be 020 030 040 50

In a potentiometer arrangement a cell of emf 1 25 volt gives a balance point at cm of length of wire If cell is replaced by another cell the balance point shifts to 63 cm What is emf of second cell O 2 25 V 1 50 V O 1 75 V 2 50 V

A resistor of resistance R is connected to an ideal battery If the value of R is decreased the power dissipated in resistor will Increase Decrease O No change Battery emf is required to find power change

Two wires of equal radii with resistivities p and p2 and length 1 and 2 respective are joined in series the equivalent resistivity of combination is P P 6 6 P P l P l P l 6 6 OP l P lz 6 6

Q 14 In the network shown below if 50 resistor is short circuited then value of Requals to Rea 60 ww ww 69 a 15 22 c 12 02 49 ww 40 ww 30 M eq 5002 1022 www 40 b 6 Q d 1 5 2 60

A wire is connected in left gap of a meter bridge balance a 100 resistor in the right gap to a point which divides the bridge wire in the ratio 3 2 The resistanc of wire is 150 18 Q 6 60 24 Q

two concentric sphere radii r1 and r2 the charge on inner sphere and outer sphere are 2micro columb and 4 micro c olumb if two sphere are connected by wires sufficient ti me then how much charge moves from inner sphere to ou ter sphere

n cells each of emfE and internal resistance r send the same current through an external resistance R whether the cells are connected in series or in parallel Then A R nr B R r C r nR D R nr E r nR

What is the equivalent resistance of the circuit 2 3 4 Correct Answer 3 our Answer 2 Status incorrect 60 70 80 90 4V 12 20 HFww 402 ww V 202 www 202 ww

3 An n p n transistor is used in common emitter configuration as an amplifier with 1k2 load resistance Signal voltage of 10mV is applied across the base emitter This produces a 3m4 change in the collector current and 15u4 change in the base current of the amplifier The input resistance in kilo ohm is

35 In the given arrangement of an experiment of a meter bridge if AC corresponding to null deflection of galvanometer is x what would be its value if radius of the wire AB is doubled THE a X A R www b 2x x C R www c 4 x B d 72

a In the figure what value must R have if the current in the circuit is to be 1 2 mA Take 2 4 V 2 4 8 V and r 4 002 b What is the rate at which thermal energy appears in R a Number w i Units S

49 In R L C series circuit the potential differences across each element is 20 V Now the value of the resistance alone is doubled then P D across R L an C respectively a 20 V 10 V 10 V c 20 V 40 V 40 V b 20 V 20 V 20 V d 10 V 20 V 20 V Karnataka CE

34 The given figure shows a spherical Gaussian surface and a charge distribution When calculating the flux of electric field through the Gaussian surface then the electric field will be due to a 93 alone c 9 93 and 92 b q and 93 d q and 9 91 1 92 AMU 2012

V IV A IV 39 ww Hr 0 VB 2 OB 5V ww 7 592 6V wwwc 552 C Vc 6V In the above diagram 1 Potential at junction O is zero 2 Current in 392 is 2A 3 Current in 5 Q2 is 2 3 A 4 All the above are correct

48 In the circuit shown current through resistance 2 is i and current through resistance 30 2 is i Find the ratio sting 1 9 1 3 5 1 202 ww 2V 5V 30 2 5V 10 V 1522 ww 3 V 5 V 5 V 2 7 1 4 None of these White

In a metre bridge what is the effect on null deflection of galvanometer when the radius of the meter bridge wire is doubled a There will be no change b Null point will shift to right c Null point will shift to left d Null point will not be available

In the following circuit the difference between the readings of ammeters A and A In amp 9p found out to be Find the value of p Assume the resistances of ammeters negligible 70 200V 100V 10002 ww A 10002 150V 90V www 10002 2000

Arrange the following in ascending order of their resistances a Ammeter of range 10 A b Ideal voltmeter c voltmeter of range 100 V d Ammeter of range 1 mA 1 a b c d 3 a d c b 2 a d b c 4 b c a d