JEE Questions for Physics Current Electricity Ii Quiz 10 - MCQExams.com

The thermocouple is based in the principle of
  • Seebeck effect
  • Thomson effect
  • Peltier effect
  • Joule effect
For a thermocouple, the neutral temperature is 270° C and the temperature of its cold junction is 20° C. If there is no deflection in the galvanometer, the temperature of the hot junction should be
  • 210° C
  • 540° C
  • 520° C
  • 209° C
In a thermocouple, the neutral temperature is 270° C and the temperature of inversion is 525° C. The temperature of cold junction would be
  • 30° C
  • 255° C
  • 15° C
  • 25° C
The direction of current in an iron-copper thermocouple is
  • From copper to iron at the hot junction
  • From iron to copper at the hot junction
  • From copper to iron at cold junction
  • No current will flow
Peltier coefficient for the junction of a pair of metals is proportional to
  • T absolute temperature of the junction
  • Square of absolute temperature of the junction

  • Physics-Current Electricity II-67146.png

  • Physics-Current Electricity II-67147.png
If for a thermocouple Tn, is the neutral temperature, Tc, is the temperature of the cold junction and Ti is the temperature of inversion, then
  • Ti = 2Tn – Tc
  • Tn = Ti – 2Tc
  • Ti = Tn –Tc
  • None of these
When current is passed in antimony-bismuth couple, then
  • The junction becomes hot when the current is from bismuth to antimony
  • The junction becomes hot when current flows from antimony to bismuth
  • Both junctions become hot
  • Both junctions become cold
Thermoelectric constant of a thermocouple are α and β. Thermoelectric power at inversion temperature is
  • α
  • – α

  • Physics-Current Electricity II-67149.png

  • Physics-Current Electricity II-67150.png

Physics-Current Electricity II-67152.png
  • 100
  • 200
  • 300
  • 400
When a current of 1 ampere is passed through a conductor whose ends are maintained at temperature difference of 1°C, the amount of heat evolved or absorbed is called
  • Peltier coefficient
  • Thomson coefficient
  • Thermoelectric power
  • Thermo e.m.f.
In a thermocouple, the temperature that does not depend on the temperature of the cold junction is called
  • Neutral temperature
  • Temperature of inversion
  • Both the above
  • None of the above
In Cu-Fe couple, the flow of current at the temperature of inversion is
  • From Fe to Cu through the hot junction
  • From Cu to Fe through the hot junction
  • Maximum
  • None of the above
In Seebeck series Sb appears before Bi. In a Sb-Bi thermocouple current flows from
  • Sb to Bi at the hot junction
  • Sb to Bi at the cold junction
  • Bi to Sb at the cold junction
  • None of the above
Which of the following statement is correct
  • Both Peltier and Joule effects are reversible
  • Both Peltier and Joule effects are irreversible
  • Joule effect is reversible, whereas Peltier effect is irreversible
  • Joule effect is irreversible, whereas Peltier effect is reversible
For a given temperature difference, which of the following pairs will generate maximum thermo e.m.f.
  • Antimony-bismuth
  • Silver-gold
  • Iron-copper
  • Lead-nickel
The cold junction of a thermocouple is maintained at 10° C. No thermo e.m.f. is developed when the hot junction is maintained at 530°C. The neutral temperature is
  • 260° C
  • 270° C
  • 265° C
  • 520° C
As the temperature of hot junction of a thermo-couple is increased (while cold junction is at constant temperature), the thermo e.m.f.
  • Increases uniformly at constant rate
  • Increases slowly in the beginning and more rapidly at higher temperatures
  • Increases more rapidly in the beginning but less rapidly at higher temperatures
  • Is minimum at neutral temperature
As the temperature of hot junction increases, the thermo e.m.f.
  • Always increases
  • Always decreases
  • May increase or decrease
  • Always remains constant
The smallest temperature difference that can be measured with a combination of a thermocouple of thermo e.m.f. 30µV per degree and a galvanometer of 50 ohm resistance, capable of measuring a minimum current of 3 × 10–7 amp is
  • 0.5 degree
  • 1.0 degree
  • 1.5 degree
  • 2.0 degree
Antimony and bismuth are usually used in a thermocouple, because
  • Negative thermal e.m.f. is produced
  • Constant thermal e.m.f. is produced
  • Lower thermal e.m.f. is produced
  • Higher thermal e.m.f. is produced
Above neutral temperature, thermo e.m.f. in a thermocouple
  • Changes sign
  • Decreases with rise in temperature
  • Increases with rise in temperature
  • Remains constant
For a thermocouple the neutral temperature is 270°C when its cold junction is at 20°C. What will be the neutral temperature and the temperature of inversion when the temperature of cold junction is increased to 40°C?
  • 290° C, 580° C
  • 270° C, 580° C
  • 270° C, 500° C
  • 290° C, 540° C
Consider the following two statements A and B and identify the correct choice given in the answers
A. Duddells thermo-galvanometer is suitable to measure direct current only
B. Thermopile can measure temperature differences of the order of 10–3° C
  • Both A and B are true
  • Both A and B are false
  • A is true but B is false
  • A is false but B is true
The inversion temperature of a copper-iron thermocouple is 540° C when the cold junction temperature is 0° C. If the cold junction temperature is increased by 10° C, then the inversion temperature and neutral temperature of the thermocouple respectively are
  • 270° C and 530° C
  • 270° C and 550° C
  • 280° C and 530° C
  • 280° C and 550° C
The resistance of the filament of an electric bulb changes with temperature. If an electric bulb rated 220 volt and 100 watt is connected to (220 × 0.volt sources, then the actual power would be
  • 100 × 0.8 watt
  • 100 × (0.8)2 watt
  • Between 100 × 0.8 watt and 100 watt
  • Between 100 × (0.8)2 watt and 100 × 0.8 watt
An immersion heater is rated 836 watt. It should heat 1 litre of water from 10° C to 40° C in about
  • 200 sec
  • 150 sec
  • 836 sec
  • 418 sec
A house is served by 220 V supply line in a circuit protected by a 9 ampere fuse. The maximum number of 60 W lamps in parallel that can be turned on, is
  • 44
  • 20
  • 22
  • 33
Water boils in an electric kettle in 15 minutes after switching on. If the length of the heating wire is decreased to 2/3 of its initial value, then the same amount of water will boil with the same supply voltage in
  • 15 minutes
  • 12 minutes
  • 10 minutes
  • 8 minutes
In the circuit as shown in the figure, the heat produced by 6 ohm resistance due to current flowing in it is 60 calorie per second. The heat generated across 3 ohm resistance per second will be
Physics-Current Electricity II-67162.png
  • 30 calorie
  • 60 calorie
  • 100 calorie
  • 120 calorie
A 500 W heating unit is designed to operate from a 115 volt line. If the line voltage drops to 110 volt, the percentage drop in heat output will be
  • 10.20%
  • 8.1%
  • 8.6%
  • 7.6%
A heater of 220 V heats a volume of water in 5 minute time. A heater of 110 V heats the same volume of water in
  • 5 minutes
  • 8 minutes
  • 10 minutes
  • 20 minutes
An electric kettle takes 4 A current at 220 V. How much time will it take to boil 1 kg of water from room temperature 20° C? The temperature of boiling water is 100° C
  • 0.63 minutes
  • 6.3 minutes
  • 12.6 minutes
  • 12.8 minutes
If a wire of resistance 20 Ω is covered with ice and a voltage of 210 V is applied across the wire, then the rate of melting of ice is
  • 0.85 g/s
  • 1.92 g/s
  • 6.56 g/s
  • All of these
Four identical electrical lamps are labelled 1.5 V, 0.5 A which describes the condition necessary for them to operate at normal brightness. A 12 V battery of negligible internal resistance is connected to lamps as shown, then
Physics-Current Electricity II-67168.png
  • The value of R for normal brightness of each lamp is (3/Ω
  • The value of R for normal brightness of each lamp is (21/Ω
  • Total power dissipated in circuit when all lamps are normally bright is 24 W
  • Power dissipated in R is 21 W when all lamps are normally bright
A 100 W bulb B1, and two 60-W bulbs B2 and B3, are connected to a 250 V source, as shown in the figure. Now W1, W2 and W3 are the output powers of the bulbs B1, B2 and B3, respectively. Then
Physics-Current Electricity II-67170.png
  • W1 > W2 = W3
  • W1 > W2 > W3
  • W1 < W2 = W3
  • W1 < W2 < W3
The three resistances of equal values are arranged in different combinations shown below. Arrange them in increasing order of power dissipation
Physics-Current Electricity II-67172.png
  • III < II < W < I
  • II < III < IV < I
  • I < lV < III < II
  • I < III < II < IV
Silver and copper voltameters are connected in parallel with a battery of e.m.f. 12 V. In 30 minutes, lg of silver and 1.8g of copper are liberated. The power supplied by the battery is
(ZCu = 6.6 × 10–4 g/C and ZAg = 11.2 × 10–4 g/C)
  • 24.13 J/sec
  • 2.413 J/sec
  • 0.2413 J/sec
  • 2413 J/sec
A silver voltameter of resistance 2 ohm and a 3 ohm resistor are connected in series across a cell. If a resistance of 2 ohm is connected in parallel with the voltameter, then the rate of deposition of silver
  • Decreases by 25%
  • Increases by 25%
  • Increases by 37.5%
  • Decreases by 37.5%
A wire of length L and 3 identical cells of negligible internal resistances are connected in series. Due to the current, the temperature of the wire is raised by ΔT in a time t. A number N of similar cells is now connected in series with a wire of the same material and cross-section but of length 2L. The temperature of the wire is raised by the same amount ΔT in the same time t. The value of N is
  • 4
  • 6
  • 8
  • 9

Physics-Current Electricity II-67177.png

  • Physics-Current Electricity II-67178.png
  • 2)
    Physics-Current Electricity II-67179.png

  • Physics-Current Electricity II-67180.png

  • Physics-Current Electricity II-67181.png
A heater is operated with a power of 1000 W in a 100 V line. It is connected in combination with a resistance of 10 Ω and a resistance R to a 100 V line as shown in figure. What should be the value of R so, that the heater operates with a power of 62.5 W
Physics-Current Electricity II-67183.png
  • 10 Ω
  • 62.5 Ω

  • Physics-Current Electricity II-67184.png
  • 5 Ω
The thermo e.m.f. of a thermo-couple is 25µV/° C at room temperature. A galvanometer of 40 ohm resistance, capable of detecting current as low as 10–5 A, is connected with the thermocouple. The smallest temperature difference that can be detected by this system is
  • 20° C
  • 16° C
  • 12° C
  • 8° C
An electric bulb rated for 500 watts at 100 volts is used in a circuit having a 200-volt supply. The resistance R that must be put in series with the bulb, so that the bulb draws 500 W is
  • 10 Ω
  • 20 Ω
  • 50 Ω
  • 100 Ω
A thermo couple develops 200 µV between 0° C and 100°C. If it develops 64 µV and 76 µV respectively between (0° C – 32° C) and (32° C – 70° C) then what will be the thermo emf it develops between 70°C and 100°C?
  • 65 µV
  • 60 µV
  • 55 µV
  • 50 µV
A thermocouple is formed by two metals X and Y, metal X comes earlier to Y in Seebeck series. If temperature of hot junction increases beyond the temperature of inversion, then direction of current in thermocouple will be from
  • X to Y through cold junction
  • X to Y through hot junction
  • Y to X through cold junction
  • Both (b) and (c)
Consider a cylindrical element as shown in the figure. Current flowing through element is I and resistivity of material of the cylinder is ρ. Choose the correct option out the following
Physics-Current Electricity II-67189.png
  • Power loss in second half is four times the power loss in first half
  • Voltage drop in first half is twice of voltage drop in second half
  • Current density in both halves are equal
  • Electric field in both halves is equal
Resistance of a voltameter is 2Ω, it is connected in series to a battery of 10 V through a resistance of 3Ω. In a certain time mass deposited on cathode is 1g. Now the voltameter and the 3Ω resistance are connected in parallel with the battery. Increase in the deposited mass on cathode in the same time will be
  • 0
  • 1.5 g
  • 2.5 g
  • 2 g
A current of 1.5 A flows through a copper voltameter. The thickness of copper deposited on the electrode surface of area 50 cm2 in 20 minutes will be (Density of copper = 9000 kg/m3 and E.C.E. of copper = 0.00033 g/C)
  • 2.6 × 10–5 m
  • 2.6 × 10–4 m
  • 1.3 × 10–5 m
  • 1.3 × 10–4 m
An ammeter, suspected to give inaccurate reading, is connected in series with a silver voltameter. The ammeter indicates 0.54 A. A steady current passed for one hour deposits 2.0124 g of silver. If the E.C.E. of silver is 1.118 × 10–3 g/C–1, then the error in ammeter reading is
  • + 0.04 A
  • + 0.02 A
  • –0.03 A
  • –0.01 A
If 1 A of current is passed through CuSO4 solution for 10 seconds, then the number of copper ions deposited at the cathode will be about
  • 1.6 × 1019
  • 3.1 × 1019
  • 4.8 × 1019
  • 6.2 × 1019
0:0:1


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