Tiêu đề 18. Current Eleciticity Easy 2.pdf ✅

1. A galvanometer having a resistance of 8 ohm is shunted by a wire of resistance 2 ohm. If the total current is 1 amp, the part of it passing through the shunt will be (a) 0.25 amp (b) 0.8 amp (c) 0.2 amp (d) 0.5 amp 2. A potentiometer wire has length 10 m and resistance 20  . A 2. 5 V battery of negligible internal resistance is connected across the wire with an 80  series resistance. The potential gradient on the wire will be (a) 5 10 V / mm −5  (b) 2.5 10 V / cm −4  (c) 0.62 10 V / mm −4  (d) 1 10 V / mm −5  3. An ammeter whose resistance is 180  gives full scale deflection when current is 2 mA. The shunt required to convert it into an ammeter reading 20 mA (in ohms) is (a) 18 (b) 20 (c) 0.1 (d) 10 4. A galvanometer whose resistance is 120  gives full scale deflection with a current of 0.05 A so that it can read a maximum current of 10 A. A shunt resistance is added in parallel with it. The resistance of the ammeter so formed is (a) 0.06  (b) 0.006  (c) 0.6  (d) 6  s 5. In a potentiometer experiment, the galvanometer shows no deflection when a cell is connected across 60 cm of the potentiometer wire. If the cell is shunted by a resistance of 6  , the balance is obtained across 50 cm of the wire. The internal resistance of the cell is (a) 0.5  (b) 0.6  (c) 1.2 (d) 1.5  6. A voltmeter of resistance 1000  gives full scale deflection when a current of 100 mA flow through it. The shunt resistance required across it to enable it to be used as an ammeter reading 1 A at full scale deflection is (a) 10000  (b) 9000  (c) 222  (d) 111  7. The resistance of 10 metre long potentiometer wire is 1ohm/meter. A cell of e.m.f. 2.2 volts and a high resistance box are connected in series to this wire. The value of resistance taken from resistance box for getting potential gradient of 2.2 millivolt/metre will be (a) 790  (b) 810  (c) 990  (d) 1000  8. We have a galvanometer of resistance 25  . It is shunted by a 2.5 wire. The part of total current that flows through the galvanometer is given as (a) 11 1 0 = I I (b) 10 1 0 = I I (c) 11 3 0 = I I (d) 11 4 0 = I I 9. In the adjoining circuit, the e.m.f. of the cell is 2 volt and the internal resistance is negligible. The resistance of the voltmeter is 80 ohm. The reading of the voltmeter will be (a) 0.80 volt (b) 1.60 volt (c) 1.33 volt (d) 2.00 volt 10. If the resistivity of a potentiometer wire be  and area of cross-section be A, then what will be potential gradient along the wire (a) A I (b) A I (c)  IA (d) IA 11. A voltmeter has resistance of 2000 ohms and it can measure upto 2V. If we want to increase its range to 10 V, then the required resistance in series will be (a) 2000  (b) 4000  (c) 6000  (d) 8000  12. For a cell of e.m.f. 2V, a balance is obtained for 50 cm of the potentiometer wire. If the cell is shunted by a 2  resistor and the balance is obtained across 40 cm of the wire, then the internal resistance of the cell is (a) 0.25  (b) 0.50 (c) 0.80  (d) 1.00  13. The arrangement as shown in figure is called as (a) Potential divider (b) Potential adder (c) Potential substracter (d) Potential multiplier 14. A potentiometer wire of length 1m and resistance 10  is connected in series with a cell of emf 2V with internal resistance 1  and a resistance box including a resistance R. If potential difference between the ends of the wire is 1 mV, the value of R is (a) 20000  (b) 19989  (c) 10000  (d) 9989  + – 2V 80  20  80  V Variable P.D. Total P.D.
15. In a balanced Wheatstone’s network, the resistances in the arms Q and S are interchanged. As a result of this (a) Network is not balanced (b) Network is still balanced (c) Galvanometer shows zero deflection (d) Galvanometer and the cell must be interchanged to balance 16. The ammeter A reads 2 A and the voltmeter V reads 20 V. the value of resistance R is (Assuming finite resistance's of ammeter and voltmeter) (a) Exactly 10 ohm (b) Less than 10 ohm (c) More than 10 ohm (d) We cannot definitely say 17. The resistance of a galvanometer coil is R. What is the shunt resistance required to convert it into an ammeter of range 4 times (a) 5 R (b) 4 R (c) 3 R (d) 4 R 18. If an ammeter is connected in parallel to a circuit, it is likely to be damaged due to excess (a) Current (b) Voltage (c) Resistance (d) All of these 19. In the given figure, battery E is balanced on 55 cm length of potentiometer wire but when a resistance of 10  is connected in parallel with the battery then it balances on 50 cm length of the potentiometer wire then internal resistance r of the battery is (a) 1  (b) 3  (c) 10  (d) 5  20. A galvanometer with a resistance of 12  gives full scale deflection when a current of 3 mA is passed. It is required to convert it into a voltmeter which can read up to 18 V. the resistance to be connected is (a) 6000  (b) 5988  (c) 5000  (d) 4988  21. The resistance of an ideal ammeter is (a) Infinite (b) Very high (c) Small (d) Zero 22. A galvanometer of 25  resistance can read a maximum current of 6mA. It can be used as a voltmeter to measure a maximum of 6 V by connecting a resistance to the galvanometer. Identify the correct choice in the given answers (a) 1025  in series (b) 1025  in parallel (c) 975  in series (d) 975  in parallel 23. A galvanometer has a resistance of 25 ohm and a maximum of 0.01 A current can be passed through it. In order to change it into an ammeter of range 10 A, the shunt resistance required is (a) 5/999 ohm (b) 10/999 ohm (c) 20/999 ohm (d) 25/999 ohm 24. In the circuit shown, a meter bridge is in its balanced state. The meter bridge wire has a resistance 0.1 ohm/cm. The value of unknown resistance X and the current drawn from the battery of negligible resistance is (a) 6 , 5 amp (b) 10 , 0.1 amp (c) 4 , 1.0 amp (d) 12 , 0.5 amp 25. A galvanometer has 30 divisions and a sensitivity 16 A / div. It can be converted into a voltmeter to read 3 V by connecting (a) Resistance nearly 6 k  in series (b) 6 k  in parallel (c) 500  in series (d) It cannot be converted 26. Voltmeters V1 and V2 are connected in series across a D.C. line. V1 reads 80 volts and has a per volt resistance of 200 ohms. V2 has a total resistance of 32 kilo ohms. The line voltage is (a) 120 volts (b) 160 volts (c) 220 volts (d) 240 volts 27. A potentiometer having the potential gradient of 2 mV/cm is used to measure the difference of potential across a resistance of 10 ohm. If a length of 50 cm of the potentiometer wire is required to get the null point, the current passing through the 10 ohm resistor is (in mA) (a) 1 (b) 2 (c) 5 (d) 10 28. An ammeter gives full deflection when a current of 2 amp. flows through it. The resistance of ammeter is 12 ohms. If the same ammeter is to be used for measuring a maximum current of 5 amp., then the ammeter must be connected with a resistance of (a) 8 ohms in series (b) 18 ohms in series R A V A 2 V E r B 1 m A B 40 cm 60 cm X 6 5V G
(c) 8 ohms in parallel (d) 18 ohms in parallel 29. In a circuit 5 percent of total current passes through a galvanometer. If resistance of the galvanometer is G then value of the shunt is (a) 19 G (b) 20 G (c) 20 G (d) 19 G 30. A voltmeter having resistance of 50 × 103 ohm is used to measure the voltage in a circuit. To increase the range of measurement 3 times the additional series resistance required is (a) 105 ohm (b) 150 k.ohm (c) 900 k.ohm (d) 9 × 106 ohm 31. In a potentiometer experiment two cells of e.m.f. E1 and E2 are used in series and in conjunction and the balancing length is found to be 58 cm of the wire. If the polarity of E2 is reversed, then the balancing length becomes 29 cm. The ratio 2 1 E E of the e.m.f. of the two cells is (a) 1 : 1 (b) 2 : 1 (c) 3 : 1 (d) 4 : 1 32. A milliammeter of range 10 mA has a coil of resistance 1 . To use it as voltmeter of range 10 volt, the resistance that must be connected in series with it, will be (a) 999  (b) 99  (c) 1000  (d) None of these 33. A voltmeter has a range 0-V with a series resistance R. With a series resistance 2R, the range is 0-V. The correct relation between V and V is (a) V = 2V (b) V  2V (c) V  2V (d) V' 2V 34. The measurement of voltmeter in the following circuit is (a) 2.4 V (b) 3.4 V (c) 4.0 V (d) 6.0 V 35. A 36  galvanometer is shunted by resistance of 4. The percentage of the total current, which passes through the galvanometer is (a) 8 % (b) 9 % (c) 10 % (d) 91 % 36. An ammeter and a voltmeter of resistance R are connected in series to an electric cell of negligible internal resistance. Their readings are A and V respectively. If another resistance R is connected in parallel with the voltmeter (a) Both A and V will increase (b) Both A and V will decrease (c) A will decrease and V will increase (d) A will increase and V will decrease 37. A wire of length 100 cm is connected to a cell of emf 2 V and negligible internal resistance. The resistance of the wire is 3 . The additional resistance required to produce a potential drop of 1 milli volt per cm is (a) 60  (b) 47  (c) 57  (d) 35  38. A galvanometer of resistance 20  is to be converted into an ammeter of range 1 A. If a current of 1 mA produces full scale deflection, the shunt required for the purpose is (a) 0.01  (b) 0.05  (c) 0.02  (d) 0.04  39. There are three voltmeters of the same range but of resistances 10000  , 8000  and 4000  respectively. The best voltmeter among these is the one whose resistance is (a) 10000  (b) 8000  (c) 4000  (d) All are equally good 40. If an ammeter is to be used in place of a voltmeter then we must connect with the ammeter a (a) Low resistance in parallel (b) High resistance in parallel (c) High resistance in series (d) Low resistance in series 41. A 10 m long wire of 20 resistance is connected with a battery of 3 volt e.m.f. (negligible internal resistance) and a 10  resistance is joined to it is series. Potential gradient along wire in volt per meter is (a) 0.02 (b) 0.3 (c) 0.2 (d) 1.3 42. A potentiometer has uniform potential gradient across it. Two cells connected in series (i) to support each other and (ii) to oppose each other are balanced over 6m and 2m respectively on the potentiometer wire. The e.m.f.’s of the cells are in the ratio of (a) 1 : 2 (b) 1 : 1 (c) 3 : 1 (d) 2 : 1 43. The material of wire of potentiometer is (a) Copper (b) Steel (c) Manganin (d) Aluminium 6V 60 + – 40 V
44. To convert a galvanometer into a voltmeter, one should connect a (a) High resistance in series with galvanometer (b) Low resistance in series with galvanometer (c) High resistance in parallel with galvanometer (d) Low resistance in parallel with galvanometer 45. To convert a 800 mV range milli voltmeter of resistance 40  into a galvanometer of 100 mA range, the resistance to be connected as shunt is (a) 10  (b) 20  (c) 30  (d) 40  46. A 100 ohm galvanometer gives full scale deflection at 10 mA. How much shunt is required to read 100 mA (a) 11.11 ohm (b) 9.9 ohm (c) 1.1 ohm (d) 4.4 ohm 47. The potential difference across the 100 resistance in the following circuit is measured by a voltmeter of 900  resistance. The percentage error made in reading the potential difference is (a) 9 10 (b) 0.1 (c) 1.0 (d) 10.0 48. A cell of internal resistance 3 ohm and emf 10 volt is connected to a uniform wire of length 500 cm and resistance 3 ohm. The potential gradient in the wire is (a) 30 mV/cm (b) 10 mV/cm (c) 20 mV/cm (d) 4 mV/cm 49. An ammeter of 100  resistance gives full deflection for the current of 10–5 amp. Now the shunt resistance required to convert it into ammeter of 1 amp. range, will be (a) 4 10 −  (b) 5 10 −  (c) 3 10 −  (d) 1 10 −  50. A galvanometer of resistance 36  is changed into an ammeter by using a shunt of 4 . The fraction f0 of total current passing through the galvanometer is (a) 40 1 (b) 4 1 (c) 140 1 (d) 10 1 51. If the ammeter in the given circuit reads 2 A, the resistance R is (a) 1 ohm (b) 2 ohm (c) 3 ohm (d) 4 ohm 52. A 50 ohm galvanometer gets full scale deflection when a current of 0.01 A passes through the coil. When it is converted to a 10 A ammeter, the shunt resistance is (a) 0.01  (b) 0.05  (c) 2000  (d) 5000  53. Resistance in the two gaps of a meter bridge are 10 ohm and 30 ohm respectively. If the resistances are interchanged the balance point shifts by (a) 33.3 cm (b) 66.67cm (c) 25 cm (d) 50 cm 54. A potentiometer has uniform potential gradient. The specific resistance of the material of the potentiometer wire is 10–7 ohm–meter and the current passing through it is 0.1 ampere; cross-section of the wire is 10–6 m2 . The potential gradient along the potentiometer wire is (a) 4 10 − V/m (b) 6 10 − V/m (c) 2 10 − V/m (d) 8 10 − V/m 55. Two resistances of 400  and 800  are connected in series with 6 volt battery of negligible internal resistance. A voltmeter of resistance 10,000  is used to measure the potential difference across 400 . The error in the measurement of potential difference in volts approximately is (a) 0.01 (b) 0.02 (c) 0.03 (d) 0.05 56. A galvanometer, having a resistance of 50  gives a full scale deflection for a current of 0.05 A. The length in meter of a resistance wire of area of cross-section 2.97× 10–2 cm2 that can be used to convert the galvanometer into an ammeter which can read a maximum of 5 A current is (Specific resistance of the wire = 5 × 7 10 − m) (a) 9 (b) 6 (c) 3 (d) 1.5 57. An ammeter reads upto 1 ampere. Its internal resistance is 0.81 ohm. To increase the range to 10 A the value of the required shunt is (a) 0.09  (b) 0.03  (c) 0.3  (d) 0.9  58. The length of a wire of a potentiometer is 100 cm, and the emf 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) 100 30 E 900  100  10  V 6 R 3 6V A