Current Electricity Questions and Answers

In the circuit shown the 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 402 mir P wwwwwww 352 wwwww 0 5 www 0 52 1 0 5 volts 1 5 volts N X www 1Q M 2 3 2 volts 4 1 0 volt

22 What should be the current in branch BD after 22 switch S is closed Se ostrzy 152 201 1 1A 3 8A 19 B 352 S 252 402 25V 2 2A 4 Zero 3x7 4 zry 63

The circuit shown here has two batteries of 8 V 16 V and three resistors 30 90 and on and a capacitor of 5 F how much is current i in the circuit in steady state 1 1 6A Check all that apply 000 A B C S 2 0 67A HHM SpF 902 3 2 5A 16V 4 0 25 A

The length of potentiometer wire is L A cell of emf e is balanced at a length from the positive End of the wire Assuming there is no contribution in resistance from any part of the circuit except the potentiometer wire the balancing length fa the same cell if the length of the wire is increased by is 2 2L 1 2 1 20 15 Check all that apply A B C 3L 15 31 3 10 2L 4 2 4 5 4 point L

of four identical resistances should be used to draw maximum energy from a cell of voltage V 15 11x 1X4 B 38 www www www www P v RUI Parallel 3 15 3 x 11 33 45 15x 12

Explain with the help of a labelled circuit diagram how you will find the resistance of a combinatio of three resistors of resistances R R and R3 joined in parallel in the diagram shown below the cell and the ammeter both have negligible resistance The resistors are identical A 4F K

tration 10 A heater is designed to operate with a power of 1000 W in a 100 V line It is connected in combination with a resistance R to a 100 V mains as shown in the figure What should be the value of R such that the heater may operate with a power of 62 5 W 1092 100V Heater w R

19 The current through the 5 resistor is 522 www a 10 A 8 V b 1 A 6 V www 99 4 V c 2 5 A d 0 4 A

A car has a fresh storage battery of e m f 12 V and internal resistance 2 x 10 2 2 If the starter motor draws a current of 80 A Then the terminal voltage when the starter is on is A 9 3 V B 12 V CY 8 4 V D 10 4 V

29 The current flown through the battery connected with infinite network as shown in the figure is 10 V 1Q www 1 5 A 2 10 A 3 2 A 1Q www 292 122 ww 202 ndation imited 19 www 3202

1 16 The circuit shown in the figure is equivalent to a load of of ww 4 a ohms 3 c 4 ohms 292 492 b 813 1 ohms d 2 ohms 21

In the circuit in Figure 1 a 20 ohm resistor sits inside 114 g of pure water that is surrounded by insulating Styrofoam igure 20 0 Water 30 0 V 10 0 www 10 0 1 of 1 5 0 10 0 2 10 0 2 www ww 5 0 5 0 ww ww Part A If the water is initially at temperature 10 7 C how long will it take for its temperature to rise to 58 7 C Use 4190 J kg C as the specific heat of water and express your answer in seconds using three significant figures View Available Hint s At Submit VA O Request Answer S

Four identical cells each of emf E and internal resistance r are to be used to deliver maximum power to a load of resistance Then the maximum power that can be delivered to the load is Select an answer A B C E 16 25 E 9 25 E2 r E 2r RO PAR

The resistance between the terminal points A and B of the given infinitely long circuit will be B 3 1 1 3 1 3 2 3 192 www www 192 www 192 ww 192 www 192 102 www 122 www 192 Up to infinity

Two sources of emf 6 V and internal resistance 392 20 are connected to an external resistance R as shown If potential difference across battery A is zero then value of R is 19 222 302 A 6 V 392 B 6 V 222 www R

A particle of charge q and mass m move in a circular orbit of radius r with frequency v The ratio of th magnetic moment to angular momentum is RPMT 2014 2q m 2 q 2m 3 9 2mr 9 2m The unife

You are given a number of 14 2 resistors each capable of dissipating only 1 7 W without being destroyed What is the minimum number of such resistors that you need to combine in series or in parallel to make a 14 2 resistance that is capable of dissipating at least 14 0 W Number Units

26 In figure there is a four way key at the middle If key is thrown from situation BD to AD then how much charge will flow through point O a 24 C c 72 C b 36 C d 12 C 22 4 F DO

If two Resistors R and R ohms are connected in parallel in an electric circuit to make an R ohm resistor The value of R can be found from the equation 1 1 R R R If R is decreasing at the rate of 1 ohm sec and R is increasing at the rate of 0 5 ohm sec Predict the value of R at what rate is R changing when R 75 ohms and R 50 ohms

For the circuit shown in figure charge flown through the switch after it is closed is n C Find the value of 1 F 4 F S L 20 V 5 4 F 1 F Answer 0 1 2 3 4 5 6 7

Across a metallic conductor of non uniform cross section a constant potential difference is applied The quantity which remains constant along the conductor is a drift velocity c current density b electric field d current

11 1 1 1963 X 10 23 A battery is connected with a tangent galvanometer and a resistance in series and the deflection of the galvanometer is 60 On placing a resistance in parallel with the galvanometer the deflection is reduced to 30 If the resistance placed in parallel is 1 9th of the galvanometer resistance calculate the ratio of the series resistance and the galvanometer resistance J E E 76 Ans 2 7 notic meridian from its cg by a fine untwisted wire

A square wave current switching rapidly between 0 5 ampere and 0 5 ampere is passed through an AC ammeter Then the reading shown by it is A 0 25 ampere ST0 5 05 ampere 2 B 0 5 ampere D 0 5 x 2 ampere sin ot

The intensity of gamma radiation from a given On passing through 36 mm of lead it is reduced to 8 urc be a 9mm b 6mm c 12mm I I thickness of lead which will reduce the intensity to 2 d 18mm The will

In a balanced wheat stone bridge current in the galvanometer is zero It remains zero when 1 battery emf is increased 2 all resistances are increased by 10 ohms 3 all resistances are made five times 4 the battery and the galvanometer are interchanged A only 1 is correct C 1 3 and 4 are correct B 1 2 and 3 are correct D 1 and 3 are correct

The current I drawn from the 5 volt source will be 1002 ww I a 0 33 A c 0 67A 5 Q 1002 5 volt 2002 www 1002 b d 0 5 A 0 17A

A group of six identical cells each of emf E and internal resistance r are joined in series to form a loop The terminal voltage across each cells OE O 6E LU CO Zero

A galvanometer has a resistance of 3663 ohm A shunt S is connected across it such tha 1 34 of the total current passes through the galvanometer Then the value of shunt is Question Type Single Correct Type 1 36630 2 1110 3 107 70

volts After that it starts decreasing Determine the frequency of the voltage source Ans 1 Hz 9 An A C circuit contains only an inductor The frequency of voltage source is 159 2 Hz And Vm 100 V The inductance of the inductor is L 1 H Obtain the expression for the current flowing in the circuit Consider voltage to be V V cost Ans I 0 1cos 1000 t A

A galvanometer has a resistance of 30 ohm and a current of 2 mA is needed to give a full scale deflection What is the resistance needed to convert this galvanometer into an ammeter of 3 A range 1 70 22 3 0 7 Q 2 0 02 S 4 20 Q

28 A current of 8 A flows in a metallic conductor of cross section 1 cm and length 10 km Free electron density of copper is 5x1028 m The time taken by the electron to travel from one end of the conductor to the other is 1 108 sec 3 107 sec 2 10 sec 4 105 sec

Plane z 0 y 100 TONY X P Wide curved trace section Thin trace section L iii If the field at point P due to the thin trace section is H I sin 0 2 A m 2n a B a b 2 8 marks

A uniform wire of resistance R is stretched uniformly to n times its original length and then cut to form five wires of equal length These wires are arranged as shown in figure The effective resistance betweer points A and B is 1 nR 5 n R A B 2 4 R 5n R

A battery of e m f 2 0 V and internal resistance 0 52 is connected across a resistance of 9 52 The number of electrons flowing through the cross section of resistance per second is 1 25 x 1018 1 25 x 1017 X 2 5 1018 17

4 The length of the resistance wire is increased by 30 by stretching it What is the corresponding change in resistance of wire 1 30 3 44 2 55 4 69

25 In a gas discharge tube if 3 x 1018 electrons are flowing pe sec from left to right and 2 x 10 8 protons are flowing p second from right to left through a given cross section Th magnitude and direction of current through the cross sectic a 0 48 left to right b 0 48 A right to left c 0 80A left to right d 0 80 A right to left

0 b a d 1 5 V decrease the range of an ammeter its resistance need to be increased An ammeter has resistance R and range I Which of the following resistance can be connected in series with it to decrease its range to R n R n 1 Ro n 1 None of these n electric bulbs are connected one by one across rence V At that time power con respectively Now if series CO

Given 1 47E0 9 x 10 Nm C Q6 What is electrostatic shielding Explain one application of it Q7 A potential difference of 4 Volt is applied across a copper wire of length 4 m Calculate potential gradient along the wire 2 2 2

The reading of voltmeter in the circuit shown is 6 V 1 2 25 V 2 3 25 V 40 2 wwww 60 2 www V 40 Q 3 4 25 V 4 6

The value of the potential difference across a conductor is 28 V A current of 7 A is passing through it What is the conductance of the given conductor O 0 259 O 0 759 O 0 50 O 19

1 25 minute 3 12 minute 4 12 5 minute 12 In a house individual power of two elements are 100 W and 150 W Effective power of their series combination will be 1 120 W 3 50 W 2 75 W 4 60 W of power 60 and 100 W respectively each rated 110 V are connected in series with the supply

A hollow copper tube of 10 m length has an external diameter of 20 cm and its walls are 10 mm thick Th specific resistance of copper is 1 7 x 10 8 Q m The resistance of the copper tube is approximately O 5 6 x 10 30 O 5 55 10 50 O 2 8 10 Q 2 85 10 50

Three light bulbs having the ratings 40 W 200 V 50 W 200 V and 100 W 200 V are connected to a 60 supply in series What is the possible case which can happen as the supply is switched on O 40 W bulb will not fuse 100 W bulb will not fuse O All the three bulbs will light with their rate powers O Only 50 W bulb will fuse

A wire 50 cm long and 1 mm2 in cross section carries a current of 4 A when connected to a 2V battery The resistivity of the wire is 1 2 x 10 7 22 m 3 4 x 10 6 m VA 2 5 x 10 7 22 m 4 1 x 10 6 m

2 The electric resistance of a certain wire of iron is R If its length and radius both are doubled then the resistance 1 Will be doubled and the specific resistance will be halved 2 Will be halved and the specific resistance will remain unchanged 3 Will be halved and the specific resistance will be doubled 4 And the specific resistance both will remain unchanged PL Hint R and p is independent of geometry changes

A 120V line is protected by a 15A fuse What is the maximum number of 120V 500W light bulbs that can be operated at full brightness from this line A 0 B 1 C 2 D 3 coefficient of resistance for a conductor at 0 C is 0 0125 15 The tempe

The temperature coefficient of resistivity of a material is 0 0004 C 1 When the temperature of material is increased by 50 C its resistivity increases by 2 x 10 80 m The initial resistivity of the material in ohm metre is 4 x 0 1 1 50 x 10 8 3 100 x 10 8 Hint Ap Past 2 90 x 10 8 4 200 x 10 8

In a Wheatstone bridge network the resistances are P 20 Q 20 R 20 and S 302 The resistance in 2 with which S is to be shunted so that the Bridge becomes balanced is A 4 B 6 C 8 D 10

The temperature coefficient of resistance for a conductor at 0 C is 0 0125 C If the resistance at 300K is R then temperature at which the resistance becomes doubled is A 407K B 802K C 647K D 600K

The p d across the terminals of the battery is 9V when a current of 3A is in th battery from negative to positive terminal When a current of 2A is in reverse direction the p d across the battery is 12V The emf and internal resistance o cell is A 54 5 V 3 5 Q B 3 5 V 54 5 Q C 11V 2 3Q D 3V