Current Electricity Questions and Answers

In the given network if an ideal battery is connected between points A and B a current i 5 6A flows through the battery If the same battery is connected between points B and C a current 1 10 5A flows through the battery The value of 10 R R lifference between A and B is D A R 2 www R www B R

ob 3 7 battery of 10 volt is connected to a resistance of 20 ohm through a variable resistance R The amount o charge which has passed in the circuit in 4 minutes if the variable resistance R is increased at the rate of ohm min is 1 120 coulomb 120 loge 2 dq V dt R dq dR V dR dt R 1 q 12 V coulomb dq 12 V 40 dR R dR R 12 V log 40 log 20 20 12 x 10 x log 2 B 120 log 2 coulomb 60 D loge 2 coulomb

When 10 4 electrons are removed from a neutral metal sphere the charge on the sphere becomes a 16 C b 16 C c 32 C d 32 C ith sill it acquires a positive charge because

If two bulbs of power 60 W and 100 W respectively each rated 110 V are connected in series with the suppl of 220 V then 1 60 W bulb will fuse 2 100 W bulb will fuse 3 Both bulbs will fuse 4 Bulbs will not fuse trio bulbo whose resistances are in the ratio 1 2 are connected in series to a constant voltage sour

a 1 5 A c 1 0 A 37 In the circuit shown below each resistance is R The current I is 15 7R a b c d b 1 5 A d 1 0 A 7V 15R 7 R 15V R Vo A www ww R ww B ww R E D R www R R www www R C

An ammeter with a scale ranging from 0 to 15 mA has a resistance of 5 2 How should the instrument be connected together with a resistor and with what resistance to measure a a current from 0 to 0 15 A b a potential difference from 0 to 150 V

A particle with charge q and mass mis projected with velocity v in opposite direction of a uniform electric field E as shown in figure in a gravity free space After what time the velocity will become v 1 2qE q S v 2 mv qE V 0

A current i in a coil varies with time t according to the graph shown in figure Which of the following graph shows the induced emf in the coil with time tv E dd at 2 I 1 do F dF R

Which of the following charge is not possible a 1 6 10 8 C b 1 6 10 9 C 1 6 10 2 C d None of these

Equivalent resistance between A and B IS each connecting arm has resistance r A 7r 1 15 3r 3 B 2 4 8r 15 16r

In the given circuit determine current through branch having indicated resistor R Given R R 422 R R R 22 E 5 V 10 V Conducting wire www R R ww e R www e R R Conducting wire

1 5 0 192 19 W ww 2 30 3V A B 252 202 3 4V Find potential difference between point A B 1 3 5 V 2 3V 3 4V 4 5V

18 Current Electricity 7 In the circuit shown in figure find potential difference across resistor R Tho 200 www Ato 26 bolos 16 totale 0 5 A 3 V T www 292 www R 222 I www 222 relle 1 6 V 6 V www 222

50 A cell can be balanced against 110 cm and 100cm of potentiometer wire respectively with and without being short circuited through a resistance of 100 Its internal resistance is 1 2 0ohm 3 1 0ohm 2 zero 4 0 5ohm

3 75 x 1019 8 An electric iron draws a current of 1 A when voltage is 100 V Calculate the amount of charge flowing through it in two hours If voltage is now changed to 400 V will it make any difference to the current flowing

18 In the circuit all bulbs consume same power If resistance of bulb 1 is 36 Q then resistance of bulb 3 and 4 are 95 B 1 4 Q 12 Q B 95 B m B 362 00 H 2 4 22 99

31 The value of current through 2 2 r sistor is 10 V 1 1 0 A 3 5 0 A 20 V 292 www 12 www 42 wwwww 2 1 5 A 1 21 A

Thus the resistivity of copper is 1 7 x 10 8 ohm metre Sample Problem 2 A copper wire has a diameter of 0 5 mm and resistivity of 1 6 10 8 2 m a What will be the length of this wire to make its resistance 10 22 b How much does the resistance change if the diameter is doubled NCERT Book Questi will calculate the area of cross section of the copper wire Here the diame

In the circuit the cells E and E have emfs 4V and 8V and internal resistance 0 5 and 192 respectively P D across E and E will be 4V 0 5 A E 4 592 a 4 25V 4 25V c 4 25V 7 5V 8V 1Q HE 3Q 652 B b 3 75V 3 75V d 3 75V 7 5V

The preparation of LiOH by the electrolysis of a 35 solution of LiCl using a platinum anode led to a current efficiency of 80 What weight of LiOH was formed by the passage of 2 5 A for 4825 s a 1 92 g c 0 96 g b 2 40 g d 0 672 g

Find equivalent resistance between points A and B Values of resistances in ohms are as shown A 292 B C D 452 30 None of these A 6 3 ww 10 2 ww 2 5 VO www www www 3 wwwww 2 5 www www B 10

3 A 6 V battery is connected to the terminals of a 3 m long wire of uniform thickness and resistance of 100 Q along with another 100 22 resistor in series The difference of potentials between two points on the wire separated by a distance of 50 cm will be 1 2 V 2 3 V 3 1 V 4 0 5 V Hint Half of the potential in 3 V is evenly distributed along the length of the wire

E are Two cells of emf E and E E connected individually to a potentiometer and their corresponding balancing length are 625 cm and 500 cm then the ratio 1 5 4 2 3 1 3 5 1 4 4 5 E E 2 is

A lightning strike transfers 10 C of charge to the ground in 2 ms Calculate the current during this lightning strike

A carbon resistor of 47 4 7 k is to be marked with rings of different colours for its identification NEET 2018 The colour code sequence will be 1 Violet Yellow Orange Silver 2 Yellow Violet Orange Silver Violet Gold

5 A simple potentiometer circuit is shown in the figure The internal resistance of the 4 V battery is negligible AB is a uniform wire of length 100 cm and resistance 2 2 What would be the length AC for zero galvanometer deflection 1 78 5 cm 3 82 5 cm 2 84 5 cm 4 80 5 cm

Two cylindrical conductors A and B of the same diameter length L and 2L and different materials of resistivity p and 5 p are connected in series with a battery of EMF 28 V If L 25 cm the magnitude of electric field in conductor A is 4 EA N C

The current density across a cylindrical conduct radius R varies in magnitude according to the equation wherer is the distance from the central J J 1 5 R axis Thus the current density is a maximum J at that axis r 0 and decreases linearly to zero at the surface r R Calculate the current in terms of J and the conductor s cross sectional area A R

Example 23 29 A galvanometer gives full scale deflection with 0 006 A current By connecting it to a 4990 2 resistance it can be converted into a 2n 2 resistance it becomes an voltmeter of range 0 30 V If connected to a 249 un 2nd oala 02 Tw ammeter of range 0 1 5 A The value of n is JEE 2

30V 192 til ww 10V ww 19 20 Find current through 20 resistor 1 2A 2 3A 3 3 5A 4

the resistance R in the circuit shown in Figure www random and has a triangular distribution as shown in fr r R 3 V 0 1 r ohms 90 110 constant current i 0 1 A and a constant resistance ro 100 determine the

Ifr 122 and E 10V in the network shown in figure Find the current i and current Problem 419 in the branch PQ of the circuit P r TH r r

in a unbias p n junction 1 high potential is at n side and low potential is at p side 2 high potential is at p side and low potential is at n side 3 p and n both are at same potential 4 undetermined On increasing the reverse bias to a large value in p n junction diode then value of current 1 remains fixed 2 increases slowly 3 decrease slowly 4 suddenly increase

The resultant resistance value of n resistances each of r ohms and connected in series is X When those n resistances are connected in 12parallel the resultant value is 28 1 X X n 3 n x X 2 n 4 nx

A house is fitted with certain numbers of 100 W 230 V incandescent lamps The power to the house is fed by a generator producing the power at 240 V The resistance of the wires from the generator to the house is 2 2 Find the maximum number of lamps that can be illuminated so that the voltage across none of the lamps drops below 230 V 10 TT

Find the potential of J with respect of G 1 40 V 2 60 V 3 20 V 4 30 V 60 V 64 Q 32 02 G

Two wires of the same material having lengths in the ratio of 1 2 and diameters in the ratio 2 1 are connected in series with a cell of emf 2 volt and internal resistance 1 ohm What is the ratio of the potential difference across the two wires

16 Three resistors are connected as shown in the diagra A 1 amp 522 B ww 1022 wwww wwwww 1592 1 Through the resistor 5 ohm a current of 1 ampere is flowing 1 What is the current through the other two resistors ii What is the p d across AB and across AC iii What is the total resistance SV

Three 60 W 120V light bulbs are across a 120 V power source If resistance of each bulb does not change with current then find out total power delivered to the three bulbs R 120V

In the circuit shown below 63 V 59 wwwwwwwww www 42 42 wwwwwwww 3Q 322 22 1 5 2 resistor is 1A 2 52 resistor is 2A 3 22 resistor is 1A

12 On resistors print 6E7 or 6R7 or 6K7 respectively mean that value of resistances are 1 6 7 2 6 70 6 7k 2 6 7 92 679 6 7k 3 67 2 6 70 67kQ 4 6 7 22 670 67kQ

In the given circuit in figure all batteries have emf and internal resistance negligible All resistors are in ohm Calculate the current in the rightmost 2 2 resistor 10 V 252 202 www 252 10 V 29 www 10 V H 252 www 10 V 2S2 10 V

An inductor 20 mH a capacitor 100 uF and a resistor 50 Q are connected in series across a source of emf V 10 sin314t The power loss in the circuit is NEET 2018 1 0 79 W 3 1 13 W 2 0 43 W 4 2 74 W

3 A B B C 4 A B B C SV R 20 BI E 2KQ IKO Find the value of resistance R when VCE 2V VBE 0 7V B 50 1 1000 2 165 4KQ 3 2150 4 100K

In the arrangment of resistances shown below the effective resistance between points A and B is 50 M 100 www www 100 100 200 W www 1002 B

For a cell of emf 2 V a balance point is obtained for 50 cm of the potentiometer wire If the cell is shunted in parallel by a 2 2 resistor and the balance is obtained across 40 cm of the wire then internal resistance of the cell is R S R 40 3 A 0 25 02 C 0 80 2 20 C d B 0 50 2 D 1 00 2

27 The current in the circuit shown is 292 2V www a 1 33 A c 2 00 A 2V 292 Fww A 201 WB JEE 2 Doubt b Zero d 1 00 A

1 An infinitely long straight wire with current I flowing along the positive z axis is located at coordinate P 12 m 5 m Determine the unit vector showing the direction of magnetic field at the origin

Equivalent resistance between A and B in the circuit shown is 1 3 8R 15 R 4 A www R www R R www www R ww www R 2 B 15R 8 4 R

15 An emf of 15 V is applied in a circuit coil containing resistance The ratio of the 5 H inductance and 10 currents at time t o and t 1s is 1 2 b a e 2 1 c 1 e 2 e e 1 d e