Q.1
The resistivity of a copper wire... [ CBSE-PMT 2002]
  • a) increases with increase in its temperature
  • b) decreases with increase in its cross-section
  • c) increases with increase in its length
  • d) increases with increase in its cross-section
Q.2
Fuse wire is a wire of .. [ CBSE-PMT 2003]
  • a)low resistance and high melting point
  • b) high resistance and low melting point
  • c)high resistance and low melting point
  • d)low resistance and low melting point
Q.3
When three identical bulbs of 60watt and 200 volts are connected in series to a 200 volt supply, the power drawn by them will be .. [ CBSE-PMT 2004]
  • a) 20 watt
  • b) 60 watt
  • c)180 watt
  • d)10 watt
Q.4
Two 220 volt, 100 watt bulbs are connected first in series and then parallel. Each time the combination is connected to 220 volt a.c. supply line. The power drawn by the combination in each case respectively will be .. [ CBSE-PMT 2003]
  • a) 50 watt, 200 watt
  • b) 50 watt, 100 watt
  • c)100 watt, 50 watt
  • d)200 watt, 150 watt
Q.5
A battery is charged at a potential of 15V for 8 hours when the current flowing is 10A. The battery on discharge supplies a current of 5A for 15 hours. The mean terminal voltage during discharge is 14V. The "watt-hour" efficiency of the battery is ... [ CBSE-PMT 2004]
  • a) 87.5%
  • b) 82.5%
  • c) 80%
  • d) 90%
Q.6
In India electricity is supplied for domestic use at 220V. It is supplied at 110V in U.S.A. If the resistance of a 60W bulb for use in India is R, the resistance of 60W bulb for use in USA will be ... [ CBSE-PMT 2004]
  • a)R/2
  • b) R
  • c)2R
  • d)R/4
Q.7
A 5 ampere fuse wire can withstand a maximum power of 1 watt in the circuit. The resistance of the fuse wire is .. [ CBSE-PMT 2005]
  • a) 0.04 Ω
  • b) 0.2 Ω
  • c)5.0 Ω
  • d)0.4 Ω
Q.8
The total power dissipated in watts in the circuit shown here is .. [ CBSE-PMT 2007]
ch-15_que_no-32_img_no1.png
  • a) 40 W
  • b) 54 W
  • c) 4 W
  • d) 16 W
Q.9
A current of 3 amp flows through the 2Ω resistor shown in the circuit. The power dissipated in the 5Ω resistor is ... [ CBSE-PMT 2008]
ch-15_que_no-34_img_no1.png
  • a) 4 watt
  • b) 2 watt
  • c)1 watt
  • d)5 watt
Q.10
The thermo e.m.f E in volts of a certain thermocouple is found to vary with temperature difference θ in °C between the two junctions according to the relation E=30 - ( θ2 / 15 )The neutral temperature for the thermocouple will be
  • a) 30°C
  • b) 450°C
  • c) 400 °C
  • d) 225°C
Q.11
If power dissipated in the 9Ω resistor in the circuit shown is 36 watt, the potential difference across the 2Ω resistor is .. [ CBSE-PMT 2011]
ch-15_que_no-37_img_no1.png
  • a)4 volt
  • b) 8 volt
  • c)10 volt
  • d)2 volt
Q.12
The rate of increase of thermo-emf with temperature at the neutral temperature of a thermo couple [ CBSE-PMT 2011]
  • a) is positive
  • b) is zero
  • c)depends upon the choice of the two materials of the thermocouple
  • d)is negative
Q.13
A thermocouple of negligible resistance produces an e.m.f. of 40µV / °C in the linear range of temperature. A galvanometer of resistance 10 Ω whose sensitivity is 1µA/div, is employed with the thermocouple. The smallest value of temperature difference that can be detected by the system will be.. [ CBSE-PMT 2011]
  • a) 0.5°C
  • b) 1.0°C
  • c)0.1°C
  • d)0.25°C
Q.14
A constant voltage is applied between the two ends of a uniform metallic wire. Some heat is developed in it. the heat developed is doubled if [ IIT 1980]
  • a)both the length and the radius of the wire are halved
  • b) both the length and the radius of the wire are doubled
  • c)the radius of the wire is doubled
  • d)the length of the wire is doubled
Q.15
In the circuit shown in figure the heat produced in the 5Ω resistor due to the current flowing through it is 10 calories per second. Heat generated in the 4Ω resistor is [ IIT 1981]
ch-15_que_no-42_img_no1.png
  • a) 1 calorie/sec
  • b) 2 calories/sec
  • c)3 calories / sec
  • d)4 calories / sec
Q.16
A piece of copper and another of germanium are cooled from room temperature to 80K. The resistance of [ IIT 1988]
  • a) each of them increases
  • b) each of them decreases
  • c)copper increases and germanium decreases
  • d)copper decreases and germanium increase
Q.17
A 100W bulb B1 and two 60W bulb B2 and B3 are connected to a 250V source, as shown in figure. Now W>1 , W2 and W3 are the output powers of the bulbs B1, B2 and B3 respectively. Then [ IIT 2002]
ch-15_que_no-44_img_no1.png
  • b) W1 > W2 > W3
  • d) W1 < W2 < W3
  • a) W₁ > W₂=W₃
  • c) W₁ < W₂=W₃
Q.18
A constant voltage is applied between the two ends of uniform metallic wire. Some heat is developed in it. The heat developed is doubled if
  • a) the radius of the wire is doubled
  • b) the length of the wire is doubled
  • c) both the length and radius of the wire are halved
  • d) both the length and radius of the wire are doubled
Q.19
The negative Zn pole of a Daniell cell, sending a constant current through a circuit, decreases in mass by 0.13g in 30 minutes. If the electrochemical equivalent of Zn and Cu are 32.5 and 31.5 respectively, the increase in the mass of the positive Cu pole in this time is [ AIEEE 2003]
  • a) 0.180 g
  • b) 0.141g
  • c)0.126g
  • d)0.242g
Q.20
A 220 Volt, 1000 watt bulb is connected across 110 Volt mains supply. The power consumed will be [ AIEEE 2003]
  • a) 750 watt
  • b) 500 watt
  • c) 250 watt
  • d) 1000 watt
Q.21
Time taken by a 836W heater to heat one litre of water from 10°C to 40°C is [ AIEEE 2004]
  • a)150 s
  • b) 100 s
  • c)50 s
  • d)200 s
Q.22
A heater coil is cut into two equal parts and only one part is now used in the heater. the heat generated will now be [ AIEEE 2009]
  • a) four times
  • b) doubled
  • c)halved
  • d)one forth
Q.23
Two voltmeter, one copper and other of silver, are joined in parallel. When a total charge q flows through the voltmeters, equal amount of metals are deposited. If the electrochemical equivalents of copper and silver are Z1 and Z2 respectively the charge which flows through the sliver voltmeter is [ AIEEE 2005]
  • a) q /{1 +(Z2 / Z1)]
  • b) q /{1 +(Z1 / Z2)]
  • c)q ( Z₂ / Z₁)
  • d)q(Z₁ / Z₂)
Q.24
A thermocouple is made from two metals, Antimony and Bismuth. If one junction of the couple is kept hot and the other is kept cold, then, an electric current will [ AIEEE 206]
  • a) flow from Antimony to Bismuth at the hot junction
  • b) flow from Bismuth to ANtimony at the cold junction
  • c) now flow through the thermocouple
  • d) flow from Antimony to Bismuth at the cold junction
Q.25
The resistance of bulb filament is 100Ω at a temperature of 100°C. If its temperature coefficient of resistance be 0.005/ °C , its resistance will become 200Ω at a temperature of [ AIEEE 2006]
  • a)300°C
  • b) 400°C
  • c)500°C
  • d)200°C
Q.26
An electric bulb is rated 220volt -100 watt. The power consumed by it when operated on 110 volt will be [ AIEEE 2006]
  • a) 75 watt
  • b) 40 watt
  • c)25 watt
  • d)5 watt
Q.27
In an ordinary heater if the length of the coil is halved, then a given quantity of water will boil is [ Andhra Medical]
  • a) less time
  • b) more time
  • c)same time
  • d)cannot be compared because specific resistance of material of wire is not given.
Q.28
The supply voltage to a room is 120V. The resistance of the lead wire is 6Ω. A 60 watt bulb is already giving light. What is the decrease in voltage across the bulb when a 240 watt heater is switched on?
  • a) zero
  • b) 2.9 volt
  • c) 13.3 volt
  • d) 10.4 volt
Q.29
A 5°C rise in temperature is observed in conductor by passing a current. When the current is doubled, the rise in temperature will be approximately [ CBSE 1998]
  • a)20°C
  • b) 16°C
  • c)12°C
  • d)10°C
Q.30
TWo identical batteries each of emf E=2V and internal resistance r=1Ω are available to produce heat in an external resistance by passing a current through it. The maximum Joulean power that can be developed across R using these batteries is [ CBSE 1990]
  • a) 1.28 W
  • b) 2W
  • c)8/9 W
  • d)3.2 W
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