| 1 |
Thermocouple is an arrangement of two different metals |
To convert heat energy in to electrical energy
To produce more heat
To convert heat energy into chemical energy
To convert electric energy in to heat energy
|
| 2 |
Current provided by a battery is maximum when |
Internal resistance equal to external resistance
Internal resistance is greater than external resistance
Internal resistance is less then external resistance
None of these
|
| 3 |
The thermistors are usually made of |
Metals with low temperature coefficient of resistivity
Metals with high temperature coefficient of resistivity
Metal oxides with high temperature coefficient of resistivity
Semi conducting materials having low temperature coefficient of resistivity
|
| 4 |
In Pakistan electricity is supplied for domestic use at 220 V, it is supplied at 110 V in USA. If the resistance of a 60 W bulb for use in Pakistan is R, the resistance of a 60 W bulb for use in USA will be |
2 R
R/4
R/2
R
|
| 5 |
When three identical bulbs of 60 watt, 200 volt rating are connected in series to a 200 volt supply, the power drawn by them will be |
180 watt
10 watt
20 watt
60 watt
|
| 6 |
Which of the following does not obey ohm's law? |
Copper
Al
Diode
None
|
| 7 |
Battery is charged in motor cars, which is based on |
Chemical effect
Magnetic effect
Electric effect
None
|
| 8 |
The minimum resistance that can be obtained by connecting 5 resistance of 1/4Ωeach is |
4/5<span style="color: rgb(34, 34, 34); font-family: "Times New Roman"; font-size: 24px; text-align: center; background-color: rgb(255, 255, 248);"><b>Ω</b></span>
5/4<span style="color: rgb(34, 34, 34); font-family: "Times New Roman"; font-size: 24px; text-align: center; background-color: rgb(255, 255, 248);"><b>Ω</b></span>
20<span style="color: rgb(34, 34, 34); font-family: "Times New Roman"; font-size: 24px; text-align: center; background-color: rgb(255, 255, 248);"><b>Ω</b></span>
0.05 <span style="color: rgb(34, 34, 34); font-family: "Times New Roman"; font-size: 24px; text-align: center; background-color: rgb(255, 255, 248);"><b>Ω</b></span>
|
| 9 |
The resistance of an incandescent lamp is |
Smaller when switched on
Greater when switched off
The same whether it is switch off or switch on
Greater when switched on
|
| 10 |
A current of 1.6 A is passed through a solution of CuSO4. How many Cu2+ions are liberated in one minute? |
3 x 10<sup>20</sup>
3 x 10<sup>10</sup>
6 x 10<sup>20</sup>
6 x 10<sup>10</sup>
|
| 11 |
A heater coil rated at (1000 W - 200 V) is connected to 110 volt line. What will be the power consumed? |
200 W
302.5
250 W
350 W
|
| 12 |
The colour sequence in a carbon resistor in red, brown, orange and silver. The resistance of the resistor is |
21 x 10<sup>3</sup><u>+</u> 10%
23 x 10<sup>1</sup><u>+</u> 10%
21 x 10<sup>3</sup><u>+</u> 5%
12 x 10<sup>3</sup><u>+</u> 5%
|
| 13 |
For two resistance wires joined in parallel, the resultant resistance is 6/5 ohm. When one of the resistance wire breaks, the effective resistance becomes 2 ohm. The resistance of the broken wire is |
3/5 ohm
2 ohm
6/5 ohm
3 ohm
|
| 14 |
A uniform resistance wire of Length L and diameter d has a resistance R. Another wire of same material has length, 4L and diameter 2d, the resistance will be |
2 R
R
R/2
R/4
|
| 15 |
Calculate the amount of charge flowing in 2 minutes in a wire of resistance 10Ωwhen a potential difference of 20 V is applied between its ends |
120 C
240 C
20 C
4 C
|
| 16 |
106electrons are moving through a wire per second, the current developed is |
1.6 x 10<sup>-19</sup>
1 A
1.6 x 10<sup>-15 </sup>A
10<sup>6</sup>A
|
| 17 |
The resistance of 20 cm long wire is 10Ω. When the length is changed to 40 cm. The new resistance is |
10<span style="color: rgb(34, 34, 34); font-family: "Times New Roman"; font-size: 24px; text-align: center; background-color: rgb(255, 255, 248);"><b>Ω</b></span>
20<span style="color: rgb(34, 34, 34); font-family: "Times New Roman"; font-size: 24px; text-align: center; background-color: rgb(255, 255, 248);"><b>Ω</b></span>
30<span style="color: rgb(34, 34, 34); font-family: "Times New Roman"; font-size: 24px; text-align: center; background-color: rgb(255, 255, 248);"><b>Ω</b></span>
40<span style="color: rgb(34, 34, 34); font-family: "Times New Roman"; font-size: 24px; text-align: center; background-color: rgb(255, 255, 248);"><b>Ω</b></span>
|
| 18 |
If two bulbs one of 60 W and other of 100 W are connected in parallel, then which one of the following will flow more? |
60 W bulb
100 W bulb
Both equally
None of these
|
| 19 |
Which one of the following causes production of heat when current is set up in a wire? |
Fall of electrons from higher orbits to lower orbits
Inter-atomic collisions
Inter-electron collisions
Collisions of conduction electron with atoms
|
| 20 |
Three resistors of resistance R each are combined in various ways. Which of the following cannot be obtained? |
3R<span style="color: rgb(34, 34, 34); font-family: "Times New Roman"; font-size: 24px; text-align: center; background-color: rgb(255, 255, 248);"><b>Ω</b></span>
2R/4<span style="color: rgb(34, 34, 34); font-family: "Times New Roman"; font-size: 24px; text-align: center; background-color: rgb(255, 255, 248);"><b>Ω</b></span>
R/3<span style="color: rgb(34, 34, 34); font-family: "Times New Roman"; font-size: 24px; text-align: center; background-color: rgb(255, 255, 248);"><b>Ω</b></span>
2R/3<span style="color: rgb(34, 34, 34); font-family: "Times New Roman"; font-size: 24px; text-align: center; background-color: rgb(255, 255, 248);"><b>Ω</b></span>
|
| 21 |
The resistance of the given conductor can be increased by |
Increasing the area
Changing resistivity
Decreasing the length
None of the above because change does not matter because in any case the volume remains the same
|
| 22 |
A 100 W, 200 V bulb is connected to a 160 volts supply. The actual power consumption would be |
64 W
80 W
100 W
125 W
|
| 23 |
A 60 W bulb operates on 220 V supply. The current flowing through the bulb is |
11/3 A
3 A
3/11 A
6
|
| 24 |
At ordinary temperature, an increase in temperature increases the conductivity of |
Conductor
Semiconductor
Insulator
Alloy
|
| 25 |
Potentiometer is more sensitive than voltmeter, because |
Voltmeter has a very high resistance
Voltmeter has a very low resistance
Potentiometer does not draw any current from a source of unknown potential difference
Potentiometer is sensitive
|
| 26 |
A car battery has e.m.f 12 volt and internal resistance 5 x 10-2ohm. If it draws 60 ampere current, the terminal voltage of the battery will be |
5 volt
3 volt
15 volt
9 volt
|
| 27 |
Specific resistance of a wire depends upon |
Length
Cross-section area
Mass
None
|
| 28 |
Cause of heat production in a current carrying conductor is |
Collisions of free electrons with one another
High drift speed of free electrons
Collisions of free electrons with atoms or ions of conductor
High resistance value
|
| 29 |
In a building, there are 15 bulbs of 40 watts, 5 bulbs of 100 watts, 5 fans of 80 watts and a heater of 1 kilowatt. The voltage of the electric main is 220 volts. The minimum efficiency of the main fuse of the building will be |
0.4 A
11.4 A
9.8 A
10.6 A
|
| 30 |
The powers of tow electric bulbs are 100 W and 200 W. Both of them are joined with 220 V mains. The ratio of resistances of their filaments will be |
1 : 2
2 : 1
1 : 4
4 : 1
|
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