Page 1 14 - CURRENT ELECTRICITY Page 1 ( Answers at the end of all questions ) 1 ) In the circuit, the galvanometer G shows zero deflection. If the batteries A and B have negligible internal resistance, the value of the resistor R will be ( a ) 100 ? ( b ) 200 ? ( c ) 1000 ? ( d ) 500? [ AIEEE 2005 ] 2 ) A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 divisions per milliampere and voltage sensitivity is 2 divisions per millivolt In order that each division reads 1 volt, the resistance in ohms needed to be connect d in series with the coil will be ( a ) 10 5 ( b ) 10 3 ( c ) 9995 ( d ) 99995 [ AIEEE 2005 ] 3 ) Two sources of equal emf are connected to an externa resistance R. The internal resistances of the two sources are R 1 and R 2 ( R 2 > R 1 ). If the potential difference across the source having internal resistance R 2 is zero, then ( a ) 1 R R R - 2 = ( b ) 2 2 1 2 R R R R R R - + × = ( c ) 1 2 2 1 R R R R R - = ( d ) 2 1 2 1 R R R R R + = [ AIEEE 2005 ] 4 ) In a potentiometer experiment the balancing with a cell is at 240 cm. On shunting the cell with a resistance of 2 ? the balancing length becomes 120 cm. The internal resistance of the cell is ( a ) 0.5 ? ( b ) 1 ? ( c 2 ? ( d ) 4 ? [ AIEEE 2005 ] 5 ) The resistance of hot tungsten ilament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not in use ? ( a ) 20 ? ( b ) 40 ? ( c ) 200 ? ( d ) 400 ? [ AIEEE 2005 ] 6 ) An energy source will upply a constant current into the load if its internal resistance is ( a ) very large as compared to the load resistance ( b ) equal to the esistance of he load ( c ) non- e o but less than the resistance of the load ( d ) ze o [ AIEEE 2005 ] 7 ) The total current supplied to the circuit by the battery is ( a ) 1 A ( b ) 2 A ( c ) 4 A d ) 6 A [ AIEEE 2004 ] 8 ) An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the lengths and radii of the wires are in the ratio of 4 / 3 and 2 / 3, then the ratio of the currents passing through the wires will be ( a ) 3 ( b ) 1 / 3 ( c ) 8 / 9 ( d ) 2 [ AIEEE 2004 ] 9 ) The resistance of the series combination of two resistors is S. When they are joined in parallel, the total resistance is P. If S = nP, then the minimum possible value of n is ( a ) 4 ( b ) 3 ( c ) 2 ( d ) 1 [ AIEEE 2004 ] www.examrace.com Page 2 14 - CURRENT ELECTRICITY Page 1 ( Answers at the end of all questions ) 1 ) In the circuit, the galvanometer G shows zero deflection. If the batteries A and B have negligible internal resistance, the value of the resistor R will be ( a ) 100 ? ( b ) 200 ? ( c ) 1000 ? ( d ) 500? [ AIEEE 2005 ] 2 ) A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 divisions per milliampere and voltage sensitivity is 2 divisions per millivolt In order that each division reads 1 volt, the resistance in ohms needed to be connect d in series with the coil will be ( a ) 10 5 ( b ) 10 3 ( c ) 9995 ( d ) 99995 [ AIEEE 2005 ] 3 ) Two sources of equal emf are connected to an externa resistance R. The internal resistances of the two sources are R 1 and R 2 ( R 2 > R 1 ). If the potential difference across the source having internal resistance R 2 is zero, then ( a ) 1 R R R - 2 = ( b ) 2 2 1 2 R R R R R R - + × = ( c ) 1 2 2 1 R R R R R - = ( d ) 2 1 2 1 R R R R R + = [ AIEEE 2005 ] 4 ) In a potentiometer experiment the balancing with a cell is at 240 cm. On shunting the cell with a resistance of 2 ? the balancing length becomes 120 cm. The internal resistance of the cell is ( a ) 0.5 ? ( b ) 1 ? ( c 2 ? ( d ) 4 ? [ AIEEE 2005 ] 5 ) The resistance of hot tungsten ilament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not in use ? ( a ) 20 ? ( b ) 40 ? ( c ) 200 ? ( d ) 400 ? [ AIEEE 2005 ] 6 ) An energy source will upply a constant current into the load if its internal resistance is ( a ) very large as compared to the load resistance ( b ) equal to the esistance of he load ( c ) non- e o but less than the resistance of the load ( d ) ze o [ AIEEE 2005 ] 7 ) The total current supplied to the circuit by the battery is ( a ) 1 A ( b ) 2 A ( c ) 4 A d ) 6 A [ AIEEE 2004 ] 8 ) An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the lengths and radii of the wires are in the ratio of 4 / 3 and 2 / 3, then the ratio of the currents passing through the wires will be ( a ) 3 ( b ) 1 / 3 ( c ) 8 / 9 ( d ) 2 [ AIEEE 2004 ] 9 ) The resistance of the series combination of two resistors is S. When they are joined in parallel, the total resistance is P. If S = nP, then the minimum possible value of n is ( a ) 4 ( b ) 3 ( c ) 2 ( d ) 1 [ AIEEE 2004 ] www.examrace.com 14 - CURRENT ELECTRICITY Page 2 ( Answers at the end of all questions ) 10 ) In a meter 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 ? ( a ) 50 cm ( b ) 80 cm ( c ) 40 cm ( d ) 70 cm [ AIEEE 2004 ] 11 ) The thermistors are usually made of ( a ) metals with low temperature coefficient of resistivity ( b ) metals with high temperature coefficient of resistivity ( c ) metal oxides with high temperature coefficient of resistivity ( d ) semiconducting materials having low temperature coefficient of esist vity [ AIEEE 2004 ] 12 ) A 3 volt battery with negligible internal resistance is connected in a circuit as shown in the figure. The cu rent ? in the circuit will be ( a ) 1 / 3 A ( b ) 1 A ( c ) 1.5 A ( d ) 2 A [ AIEEE 2003 ] 13 ) The length of a given cylindrical wire is increased by 100 %. Due to this decrease in its diameter, the change in the resistance of t e wire will be ( a ) 300 % ( b ) 200 % ( c ) 100 % ( d ) 50 % [ AIEEE 2003 ] 14 ) An ammeter reads upto 1 ampere Its internal resistance 0.81 ohm. To increase the range to 10 ampere, the value of the r quired shunt is ( a ) 0.09 ? ( b ) 0.03 ? ( c ) 0.3 ? ( d ) 0.9 ? [ AIEEE 2003 ] 15 ) The length of a wire of potentiometer is 100 cm and the e.m.f. of its standard cell is E volt. It is employed to measure the e.m.f. of a battery whose internal resistance is 0.5 ?. If the balance point is obtained at l = 30 cm from the positive end, the e.m.f. of the battery is ( a ) 0.2 E ( b ) 0 3 E ( c ) 0.4 E ( d ) 0.5 E [ AIEEE 2003 ] ( Note: The concept of potentiometer is incorrectly used in this question.) 16 ) The therm emf of a thermocouple is 25 µV / °C at room temperature. A galvanometer of 40 ?, capable of detecting current as low as 10 - 5 A, is connected with the thermocouple. The smallest temperature difference that can be detected by the system is ( a ) 20 °C ( b ) 16 °C ( c ) 12 °C ( d ) 8 °C [ AIEEE 2003 ] 17 The resistance of a coil at 100 °C is 4.2 ?. If temperature coefficient of resistance is 0.004 / °C, then its resistance at 0 °C is ( a ) 6.5 ? ( b ) 5 ? ( c ) 3 ? ( d ) 2.5 ? [ AIEEE 2002 ] 18 ) If a wire of resistance R is melted and recasted to half of its length, then the new resistance of the wire will be ( a ) R / 4 ( b ) R / 2 ( c ) R ( d ) 2 R [ AIEEE 2002 ] 19 ) A steady current flows in a metallic conductor of non-uniform cross-section. Which of the following quantity is constant along the conductor ? ( a ) current ( b ) drift speed ( c ) current density ( d ) none of these [ AIEEE 2002 ] www.examrace.com Page 3 14 - CURRENT ELECTRICITY Page 1 ( Answers at the end of all questions ) 1 ) In the circuit, the galvanometer G shows zero deflection. If the batteries A and B have negligible internal resistance, the value of the resistor R will be ( a ) 100 ? ( b ) 200 ? ( c ) 1000 ? ( d ) 500? [ AIEEE 2005 ] 2 ) A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 divisions per milliampere and voltage sensitivity is 2 divisions per millivolt In order that each division reads 1 volt, the resistance in ohms needed to be connect d in series with the coil will be ( a ) 10 5 ( b ) 10 3 ( c ) 9995 ( d ) 99995 [ AIEEE 2005 ] 3 ) Two sources of equal emf are connected to an externa resistance R. The internal resistances of the two sources are R 1 and R 2 ( R 2 > R 1 ). If the potential difference across the source having internal resistance R 2 is zero, then ( a ) 1 R R R - 2 = ( b ) 2 2 1 2 R R R R R R - + × = ( c ) 1 2 2 1 R R R R R - = ( d ) 2 1 2 1 R R R R R + = [ AIEEE 2005 ] 4 ) In a potentiometer experiment the balancing with a cell is at 240 cm. On shunting the cell with a resistance of 2 ? the balancing length becomes 120 cm. The internal resistance of the cell is ( a ) 0.5 ? ( b ) 1 ? ( c 2 ? ( d ) 4 ? [ AIEEE 2005 ] 5 ) The resistance of hot tungsten ilament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not in use ? ( a ) 20 ? ( b ) 40 ? ( c ) 200 ? ( d ) 400 ? [ AIEEE 2005 ] 6 ) An energy source will upply a constant current into the load if its internal resistance is ( a ) very large as compared to the load resistance ( b ) equal to the esistance of he load ( c ) non- e o but less than the resistance of the load ( d ) ze o [ AIEEE 2005 ] 7 ) The total current supplied to the circuit by the battery is ( a ) 1 A ( b ) 2 A ( c ) 4 A d ) 6 A [ AIEEE 2004 ] 8 ) An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the lengths and radii of the wires are in the ratio of 4 / 3 and 2 / 3, then the ratio of the currents passing through the wires will be ( a ) 3 ( b ) 1 / 3 ( c ) 8 / 9 ( d ) 2 [ AIEEE 2004 ] 9 ) The resistance of the series combination of two resistors is S. When they are joined in parallel, the total resistance is P. If S = nP, then the minimum possible value of n is ( a ) 4 ( b ) 3 ( c ) 2 ( d ) 1 [ AIEEE 2004 ] www.examrace.com 14 - CURRENT ELECTRICITY Page 2 ( Answers at the end of all questions ) 10 ) In a meter 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 ? ( a ) 50 cm ( b ) 80 cm ( c ) 40 cm ( d ) 70 cm [ AIEEE 2004 ] 11 ) The thermistors are usually made of ( a ) metals with low temperature coefficient of resistivity ( b ) metals with high temperature coefficient of resistivity ( c ) metal oxides with high temperature coefficient of resistivity ( d ) semiconducting materials having low temperature coefficient of esist vity [ AIEEE 2004 ] 12 ) A 3 volt battery with negligible internal resistance is connected in a circuit as shown in the figure. The cu rent ? in the circuit will be ( a ) 1 / 3 A ( b ) 1 A ( c ) 1.5 A ( d ) 2 A [ AIEEE 2003 ] 13 ) The length of a given cylindrical wire is increased by 100 %. Due to this decrease in its diameter, the change in the resistance of t e wire will be ( a ) 300 % ( b ) 200 % ( c ) 100 % ( d ) 50 % [ AIEEE 2003 ] 14 ) An ammeter reads upto 1 ampere Its internal resistance 0.81 ohm. To increase the range to 10 ampere, the value of the r quired shunt is ( a ) 0.09 ? ( b ) 0.03 ? ( c ) 0.3 ? ( d ) 0.9 ? [ AIEEE 2003 ] 15 ) The length of a wire of potentiometer is 100 cm and the e.m.f. of its standard cell is E volt. It is employed to measure the e.m.f. of a battery whose internal resistance is 0.5 ?. If the balance point is obtained at l = 30 cm from the positive end, the e.m.f. of the battery is ( a ) 0.2 E ( b ) 0 3 E ( c ) 0.4 E ( d ) 0.5 E [ AIEEE 2003 ] ( Note: The concept of potentiometer is incorrectly used in this question.) 16 ) The therm emf of a thermocouple is 25 µV / °C at room temperature. A galvanometer of 40 ?, capable of detecting current as low as 10 - 5 A, is connected with the thermocouple. The smallest temperature difference that can be detected by the system is ( a ) 20 °C ( b ) 16 °C ( c ) 12 °C ( d ) 8 °C [ AIEEE 2003 ] 17 The resistance of a coil at 100 °C is 4.2 ?. If temperature coefficient of resistance is 0.004 / °C, then its resistance at 0 °C is ( a ) 6.5 ? ( b ) 5 ? ( c ) 3 ? ( d ) 2.5 ? [ AIEEE 2002 ] 18 ) If a wire of resistance R is melted and recasted to half of its length, then the new resistance of the wire will be ( a ) R / 4 ( b ) R / 2 ( c ) R ( d ) 2 R [ AIEEE 2002 ] 19 ) A steady current flows in a metallic conductor of non-uniform cross-section. Which of the following quantity is constant along the conductor ? ( a ) current ( b ) drift speed ( c ) current density ( d ) none of these [ AIEEE 2002 ] www.examrace.com 14 - CURRENT ELECTRICITY Page 3 ( Answers at the end of all questions ) 20 ) Find out current in 2 ? resistance. ( a ) 0 ( b ) 2 A ( c ) 3 A ( d ) 5 A [ IIT 2005 ] 21 ) A galvanometer of resistance 100 ? is converted to an ammeter using r sistance of 0.1 ?. It gives full scale deflection at 100 µA. The minimum current i the circuit for maximum deflection is ( a ) 100.1 mA ( b ) 1000.1 mA ( c ) 1.001 mA ( d ) 10.01 mA [ IIT 2005 ] 22 ) A rigid container with thermally insulated walls contains a coil f resistance 100 ? carrying current 1 A. Change in internal energy after 5 minutes is ( a ) 0 kJ ( b ) 10 kJ ( c ) 20 kJ ( d ) 30 kJ [ IIT 2005 ] 23 ) Six equal resistors are connected between point P, Q and R as shown in the figure. Then the next esistance will be maximum between ( a ) P and Q ( b ) Q and R ( c ) P and R ( d ) any two points [ IIT 2004 ] 24 ) For the post office b x arrangement to determine the value of unknown resistance, the unknown resistance should be connected between ( a ) B and C ( b ) C and D ( c ) A and D ( d ) B 1 nd C 1 [ IIT 2004 ] 25 ) Express hich of the following set ups can be used to verify Ohmâ€™s law ? ( a ) ( b ) ( c ) ( d ) [ IIT 2003 ] 26 ) The temperature coefficient of resistance of a wire is 0.00125 per °C. At 300 K its resistance is 1 ohm. The resistance of the wire will be 2 ohm at ( a ) 1154 K ( b ) 1100 K ( c ) 1400 K ( d ) 1127 K [ IIT 1980 ] www.examrace.com Page 4 14 - CURRENT ELECTRICITY Page 1 ( Answers at the end of all questions ) 1 ) In the circuit, the galvanometer G shows zero deflection. If the batteries A and B have negligible internal resistance, the value of the resistor R will be ( a ) 100 ? ( b ) 200 ? ( c ) 1000 ? ( d ) 500? [ AIEEE 2005 ] 2 ) A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 divisions per milliampere and voltage sensitivity is 2 divisions per millivolt In order that each division reads 1 volt, the resistance in ohms needed to be connect d in series with the coil will be ( a ) 10 5 ( b ) 10 3 ( c ) 9995 ( d ) 99995 [ AIEEE 2005 ] 3 ) Two sources of equal emf are connected to an externa resistance R. The internal resistances of the two sources are R 1 and R 2 ( R 2 > R 1 ). If the potential difference across the source having internal resistance R 2 is zero, then ( a ) 1 R R R - 2 = ( b ) 2 2 1 2 R R R R R R - + × = ( c ) 1 2 2 1 R R R R R - = ( d ) 2 1 2 1 R R R R R + = [ AIEEE 2005 ] 4 ) In a potentiometer experiment the balancing with a cell is at 240 cm. On shunting the cell with a resistance of 2 ? the balancing length becomes 120 cm. The internal resistance of the cell is ( a ) 0.5 ? ( b ) 1 ? ( c 2 ? ( d ) 4 ? [ AIEEE 2005 ] 5 ) The resistance of hot tungsten ilament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not in use ? ( a ) 20 ? ( b ) 40 ? ( c ) 200 ? ( d ) 400 ? [ AIEEE 2005 ] 6 ) An energy source will upply a constant current into the load if its internal resistance is ( a ) very large as compared to the load resistance ( b ) equal to the esistance of he load ( c ) non- e o but less than the resistance of the load ( d ) ze o [ AIEEE 2005 ] 7 ) The total current supplied to the circuit by the battery is ( a ) 1 A ( b ) 2 A ( c ) 4 A d ) 6 A [ AIEEE 2004 ] 8 ) An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the lengths and radii of the wires are in the ratio of 4 / 3 and 2 / 3, then the ratio of the currents passing through the wires will be ( a ) 3 ( b ) 1 / 3 ( c ) 8 / 9 ( d ) 2 [ AIEEE 2004 ] 9 ) The resistance of the series combination of two resistors is S. When they are joined in parallel, the total resistance is P. If S = nP, then the minimum possible value of n is ( a ) 4 ( b ) 3 ( c ) 2 ( d ) 1 [ AIEEE 2004 ] www.examrace.com 14 - CURRENT ELECTRICITY Page 2 ( Answers at the end of all questions ) 10 ) In a meter 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 ? ( a ) 50 cm ( b ) 80 cm ( c ) 40 cm ( d ) 70 cm [ AIEEE 2004 ] 11 ) The thermistors are usually made of ( a ) metals with low temperature coefficient of resistivity ( b ) metals with high temperature coefficient of resistivity ( c ) metal oxides with high temperature coefficient of resistivity ( d ) semiconducting materials having low temperature coefficient of esist vity [ AIEEE 2004 ] 12 ) A 3 volt battery with negligible internal resistance is connected in a circuit as shown in the figure. The cu rent ? in the circuit will be ( a ) 1 / 3 A ( b ) 1 A ( c ) 1.5 A ( d ) 2 A [ AIEEE 2003 ] 13 ) The length of a given cylindrical wire is increased by 100 %. Due to this decrease in its diameter, the change in the resistance of t e wire will be ( a ) 300 % ( b ) 200 % ( c ) 100 % ( d ) 50 % [ AIEEE 2003 ] 14 ) An ammeter reads upto 1 ampere Its internal resistance 0.81 ohm. To increase the range to 10 ampere, the value of the r quired shunt is ( a ) 0.09 ? ( b ) 0.03 ? ( c ) 0.3 ? ( d ) 0.9 ? [ AIEEE 2003 ] 15 ) The length of a wire of potentiometer is 100 cm and the e.m.f. of its standard cell is E volt. It is employed to measure the e.m.f. of a battery whose internal resistance is 0.5 ?. If the balance point is obtained at l = 30 cm from the positive end, the e.m.f. of the battery is ( a ) 0.2 E ( b ) 0 3 E ( c ) 0.4 E ( d ) 0.5 E [ AIEEE 2003 ] ( Note: The concept of potentiometer is incorrectly used in this question.) 16 ) The therm emf of a thermocouple is 25 µV / °C at room temperature. A galvanometer of 40 ?, capable of detecting current as low as 10 - 5 A, is connected with the thermocouple. The smallest temperature difference that can be detected by the system is ( a ) 20 °C ( b ) 16 °C ( c ) 12 °C ( d ) 8 °C [ AIEEE 2003 ] 17 The resistance of a coil at 100 °C is 4.2 ?. If temperature coefficient of resistance is 0.004 / °C, then its resistance at 0 °C is ( a ) 6.5 ? ( b ) 5 ? ( c ) 3 ? ( d ) 2.5 ? [ AIEEE 2002 ] 18 ) If a wire of resistance R is melted and recasted to half of its length, then the new resistance of the wire will be ( a ) R / 4 ( b ) R / 2 ( c ) R ( d ) 2 R [ AIEEE 2002 ] 19 ) A steady current flows in a metallic conductor of non-uniform cross-section. Which of the following quantity is constant along the conductor ? ( a ) current ( b ) drift speed ( c ) current density ( d ) none of these [ AIEEE 2002 ] www.examrace.com 14 - CURRENT ELECTRICITY Page 3 ( Answers at the end of all questions ) 20 ) Find out current in 2 ? resistance. ( a ) 0 ( b ) 2 A ( c ) 3 A ( d ) 5 A [ IIT 2005 ] 21 ) A galvanometer of resistance 100 ? is converted to an ammeter using r sistance of 0.1 ?. It gives full scale deflection at 100 µA. The minimum current i the circuit for maximum deflection is ( a ) 100.1 mA ( b ) 1000.1 mA ( c ) 1.001 mA ( d ) 10.01 mA [ IIT 2005 ] 22 ) A rigid container with thermally insulated walls contains a coil f resistance 100 ? carrying current 1 A. Change in internal energy after 5 minutes is ( a ) 0 kJ ( b ) 10 kJ ( c ) 20 kJ ( d ) 30 kJ [ IIT 2005 ] 23 ) Six equal resistors are connected between point P, Q and R as shown in the figure. Then the next esistance will be maximum between ( a ) P and Q ( b ) Q and R ( c ) P and R ( d ) any two points [ IIT 2004 ] 24 ) For the post office b x arrangement to determine the value of unknown resistance, the unknown resistance should be connected between ( a ) B and C ( b ) C and D ( c ) A and D ( d ) B 1 nd C 1 [ IIT 2004 ] 25 ) Express hich of the following set ups can be used to verify Ohmâ€™s law ? ( a ) ( b ) ( c ) ( d ) [ IIT 2003 ] 26 ) The temperature coefficient of resistance of a wire is 0.00125 per °C. At 300 K its resistance is 1 ohm. The resistance of the wire will be 2 ohm at ( a ) 1154 K ( b ) 1100 K ( c ) 1400 K ( d ) 1127 K [ IIT 1980 ] www.examrace.com 14 - CURRENT ELECTRICITY Page 4 ( Answers at the end of all questions ) 27 ) In the sown arrangement of the experiment of the meter bridge if AC corresponding to null deflection of galvanometer is x, what would be its value if the radius of the wire AB is doubled ? ( a ) x ( b ) x / 4 ( c ) 4x ( d ) 2x [ IIT 2003 ] 28 ) The effective resistance between points P and Q of the electrical circuit shown in the figure is ( a ) r R Rr 2 + ( b ) r 3R ) r R ( R 8 + + ( c ) 2r + 4R ( d ) 5R /2 + 2r [ IIT 2002 ] 29 ) The potential difference applied to an X ray ube is 5 kV and the current through it is 3.2 mA. Then the number of electrons st king the target per second is ( a ) 2 ×10 16 ( b ) 5 × 10 6 ( c ) 1 × 10 7 ( d ) 4 × 10 15 [ IIT 2002 ] 30 ) In the given circuit, with st dy urrent, the potential drop across the capacitor must be ( a ) V ( b ) V / 2 ( b ) V / 3 ( d ) 2V / 3 [ IIT 2001 ] 31 ) In the given circuit, it is observed that the current ? is independent of the value of the resistance R 6 . Then the resistance values must satisfy ( a ) R 1 R 2 R 5 = R 3 R 4 R 6 ( b ) 4 3 2 1 6 5 R R 1 R R 1 R 1 R 1 + + + = + ( c ) R 1 R 4 = R 2 R 3 ( d ) R 1 R 2 = R 2 R 4 [ IIT 2001 ] 32 ) In the circuit shown, P ? R. The reading in the galvanometer is the same with switch S open or closed. Then ( a ) ? R = ? G ( b ) ? P = ? G ( c ) ? Q = ? G ( d ) ? Q = ? R [ IIT 1999 ] www.examrace.com Page 5 14 - CURRENT ELECTRICITY Page 1 ( Answers at the end of all questions ) 1 ) In the circuit, the galvanometer G shows zero deflection. If the batteries A and B have negligible internal resistance, the value of the resistor R will be ( a ) 100 ? ( b ) 200 ? ( c ) 1000 ? ( d ) 500? [ AIEEE 2005 ] 2 ) A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 divisions per milliampere and voltage sensitivity is 2 divisions per millivolt In order that each division reads 1 volt, the resistance in ohms needed to be connect d in series with the coil will be ( a ) 10 5 ( b ) 10 3 ( c ) 9995 ( d ) 99995 [ AIEEE 2005 ] 3 ) Two sources of equal emf are connected to an externa resistance R. The internal resistances of the two sources are R 1 and R 2 ( R 2 > R 1 ). If the potential difference across the source having internal resistance R 2 is zero, then ( a ) 1 R R R - 2 = ( b ) 2 2 1 2 R R R R R R - + × = ( c ) 1 2 2 1 R R R R R - = ( d ) 2 1 2 1 R R R R R + = [ AIEEE 2005 ] 4 ) In a potentiometer experiment the balancing with a cell is at 240 cm. On shunting the cell with a resistance of 2 ? the balancing length becomes 120 cm. The internal resistance of the cell is ( a ) 0.5 ? ( b ) 1 ? ( c 2 ? ( d ) 4 ? [ AIEEE 2005 ] 5 ) The resistance of hot tungsten ilament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not in use ? ( a ) 20 ? ( b ) 40 ? ( c ) 200 ? ( d ) 400 ? [ AIEEE 2005 ] 6 ) An energy source will upply a constant current into the load if its internal resistance is ( a ) very large as compared to the load resistance ( b ) equal to the esistance of he load ( c ) non- e o but less than the resistance of the load ( d ) ze o [ AIEEE 2005 ] 7 ) The total current supplied to the circuit by the battery is ( a ) 1 A ( b ) 2 A ( c ) 4 A d ) 6 A [ AIEEE 2004 ] 8 ) An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the lengths and radii of the wires are in the ratio of 4 / 3 and 2 / 3, then the ratio of the currents passing through the wires will be ( a ) 3 ( b ) 1 / 3 ( c ) 8 / 9 ( d ) 2 [ AIEEE 2004 ] 9 ) The resistance of the series combination of two resistors is S. When they are joined in parallel, the total resistance is P. If S = nP, then the minimum possible value of n is ( a ) 4 ( b ) 3 ( c ) 2 ( d ) 1 [ AIEEE 2004 ] www.examrace.com 14 - CURRENT ELECTRICITY Page 2 ( Answers at the end of all questions ) 10 ) In a meter 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 ? ( a ) 50 cm ( b ) 80 cm ( c ) 40 cm ( d ) 70 cm [ AIEEE 2004 ] 11 ) The thermistors are usually made of ( a ) metals with low temperature coefficient of resistivity ( b ) metals with high temperature coefficient of resistivity ( c ) metal oxides with high temperature coefficient of resistivity ( d ) semiconducting materials having low temperature coefficient of esist vity [ AIEEE 2004 ] 12 ) A 3 volt battery with negligible internal resistance is connected in a circuit as shown in the figure. The cu rent ? in the circuit will be ( a ) 1 / 3 A ( b ) 1 A ( c ) 1.5 A ( d ) 2 A [ AIEEE 2003 ] 13 ) The length of a given cylindrical wire is increased by 100 %. Due to this decrease in its diameter, the change in the resistance of t e wire will be ( a ) 300 % ( b ) 200 % ( c ) 100 % ( d ) 50 % [ AIEEE 2003 ] 14 ) An ammeter reads upto 1 ampere Its internal resistance 0.81 ohm. To increase the range to 10 ampere, the value of the r quired shunt is ( a ) 0.09 ? ( b ) 0.03 ? ( c ) 0.3 ? ( d ) 0.9 ? [ AIEEE 2003 ] 15 ) The length of a wire of potentiometer is 100 cm and the e.m.f. of its standard cell is E volt. It is employed to measure the e.m.f. of a battery whose internal resistance is 0.5 ?. If the balance point is obtained at l = 30 cm from the positive end, the e.m.f. of the battery is ( a ) 0.2 E ( b ) 0 3 E ( c ) 0.4 E ( d ) 0.5 E [ AIEEE 2003 ] ( Note: The concept of potentiometer is incorrectly used in this question.) 16 ) The therm emf of a thermocouple is 25 µV / °C at room temperature. A galvanometer of 40 ?, capable of detecting current as low as 10 - 5 A, is connected with the thermocouple. The smallest temperature difference that can be detected by the system is ( a ) 20 °C ( b ) 16 °C ( c ) 12 °C ( d ) 8 °C [ AIEEE 2003 ] 17 The resistance of a coil at 100 °C is 4.2 ?. If temperature coefficient of resistance is 0.004 / °C, then its resistance at 0 °C is ( a ) 6.5 ? ( b ) 5 ? ( c ) 3 ? ( d ) 2.5 ? [ AIEEE 2002 ] 18 ) If a wire of resistance R is melted and recasted to half of its length, then the new resistance of the wire will be ( a ) R / 4 ( b ) R / 2 ( c ) R ( d ) 2 R [ AIEEE 2002 ] 19 ) A steady current flows in a metallic conductor of non-uniform cross-section. Which of the following quantity is constant along the conductor ? ( a ) current ( b ) drift speed ( c ) current density ( d ) none of these [ AIEEE 2002 ] www.examrace.com 14 - CURRENT ELECTRICITY Page 3 ( Answers at the end of all questions ) 20 ) Find out current in 2 ? resistance. ( a ) 0 ( b ) 2 A ( c ) 3 A ( d ) 5 A [ IIT 2005 ] 21 ) A galvanometer of resistance 100 ? is converted to an ammeter using r sistance of 0.1 ?. It gives full scale deflection at 100 µA. The minimum current i the circuit for maximum deflection is ( a ) 100.1 mA ( b ) 1000.1 mA ( c ) 1.001 mA ( d ) 10.01 mA [ IIT 2005 ] 22 ) A rigid container with thermally insulated walls contains a coil f resistance 100 ? carrying current 1 A. Change in internal energy after 5 minutes is ( a ) 0 kJ ( b ) 10 kJ ( c ) 20 kJ ( d ) 30 kJ [ IIT 2005 ] 23 ) Six equal resistors are connected between point P, Q and R as shown in the figure. Then the next esistance will be maximum between ( a ) P and Q ( b ) Q and R ( c ) P and R ( d ) any two points [ IIT 2004 ] 24 ) For the post office b x arrangement to determine the value of unknown resistance, the unknown resistance should be connected between ( a ) B and C ( b ) C and D ( c ) A and D ( d ) B 1 nd C 1 [ IIT 2004 ] 25 ) Express hich of the following set ups can be used to verify Ohmâ€™s law ? ( a ) ( b ) ( c ) ( d ) [ IIT 2003 ] 26 ) The temperature coefficient of resistance of a wire is 0.00125 per °C. At 300 K its resistance is 1 ohm. The resistance of the wire will be 2 ohm at ( a ) 1154 K ( b ) 1100 K ( c ) 1400 K ( d ) 1127 K [ IIT 1980 ] www.examrace.com 14 - CURRENT ELECTRICITY Page 4 ( Answers at the end of all questions ) 27 ) In the sown arrangement of the experiment of the meter bridge if AC corresponding to null deflection of galvanometer is x, what would be its value if the radius of the wire AB is doubled ? ( a ) x ( b ) x / 4 ( c ) 4x ( d ) 2x [ IIT 2003 ] 28 ) The effective resistance between points P and Q of the electrical circuit shown in the figure is ( a ) r R Rr 2 + ( b ) r 3R ) r R ( R 8 + + ( c ) 2r + 4R ( d ) 5R /2 + 2r [ IIT 2002 ] 29 ) The potential difference applied to an X ray ube is 5 kV and the current through it is 3.2 mA. Then the number of electrons st king the target per second is ( a ) 2 ×10 16 ( b ) 5 × 10 6 ( c ) 1 × 10 7 ( d ) 4 × 10 15 [ IIT 2002 ] 30 ) In the given circuit, with st dy urrent, the potential drop across the capacitor must be ( a ) V ( b ) V / 2 ( b ) V / 3 ( d ) 2V / 3 [ IIT 2001 ] 31 ) In the given circuit, it is observed that the current ? is independent of the value of the resistance R 6 . Then the resistance values must satisfy ( a ) R 1 R 2 R 5 = R 3 R 4 R 6 ( b ) 4 3 2 1 6 5 R R 1 R R 1 R 1 R 1 + + + = + ( c ) R 1 R 4 = R 2 R 3 ( d ) R 1 R 2 = R 2 R 4 [ IIT 2001 ] 32 ) In the circuit shown, P ? R. The reading in the galvanometer is the same with switch S open or closed. Then ( a ) ? R = ? G ( b ) ? P = ? G ( c ) ? Q = ? G ( d ) ? Q = ? R [ IIT 1999 ] www.examrace.com 14 - CURRENT ELECTRICITY Page 5 ( Answers at the end of all questions ) 33 ) In the circuit shown in the figure, the current through ( a ) the 3? resistor is 0.50 A ( b ) the 3? resistor is 0.25 A ( c ) the 4? resistor is 0.50 A ( d ) the 4? resistor is 0.25 A [ IIT 1998 ] 34 ) The circuit shown in the figure contains two diodes each with a forward resistance of 50 ? and with infinite backward resistance. If the battery voltage is 6 V, the current through the 100 ? resistor ( in A ) is ( a ) zero ( b ) 0.02 ( c ) 0.03 ( d ) 0.036 [ IIT 1997 35 ) A steady current flows in a metallic condu tor o non-uniform cross-section. The quantity / quantities constant along the length of th conductor is / are ( a ) current, electric field and drift velocity ( b ) drift speed only ( c ) current and drift speed ( d ) current only [ IIT 1997 ] 36 ) The current i in the circuit is ( a ) 1 / 45 A ( b ) 1 / 15 A ( c ) 1 / 10 A ( d ) / 5 A [ IIT 1983 ] 37 ) A charge of 3 C experiences a force of 3000 N when it is moved in a uniform electric i ld What is the potential difference between two points separated by a distance cm ? ( a ) 10 V ( b ) 90 V ( c ) 1000 V ( d ) 100 V 38 ) A cu ent I flows in a wire of circular cross-section with the free electrons traveling with a drift velocity V. What is the drift velocity of electrons when a current 2 I flows in another wire of twice the radius and of the same material ? a ) 2 V ( b ) V ( c ) V / 2 ( d ) V / 4 39 ) A piece of copper wire is cut into ten equal parts. These parts are connected in parallel. The joint resistance of the parallel combination will be equal to the original resistance of the uncut wire, multiplied by a factor of ( a ) 0.01 ( b ) 0.1 ( c ) 1 ( d ) 10 40 ) Using the resistors R 1 and R 2 singly, in series and in parallel combination, we can get 4, 5, 20 and 25 ?. Then R 1 , R 2 are ( a ) 4, 5 ( b ) 5, 20 ( c ) 20, 25 ( d ) 25, 4 www.examrace.comRead More

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