| 1 |
The circuit in which current and voltage are in phase, the power factor is: |
Zero
1
-1
2
|
| 2 |
An electromagnetic wave goes from air to glass which of the following does not change? |
Radio waves
X-rays
Ultra violet radiation
Ultra sond waves
|
| 3 |
For electromagnetic waves, Maxwell generalized |
Gauses law for magnetism
Gauses law for eletricity
Fradays law
Amperes law
|
| 4 |
An alternating quantity (voltage or current) is completely known if we know its: |
Maximum
Frequency and phase
Effective value
Both (a) & (b)
|
| 5 |
In LR circiut which one of the following statements is correct? |
L and R opposes each other
R value increases with frequency
The inductive reactance increases with frequency
The inductive reactance decreases with frequency
|
| 6 |
An alternating voltage is given by 20 sin 157 t. Th efrequency of alternating voltage is: |
50 Hz
25Hz
100 Hz
75 Hz
|
| 7 |
The phase difference between the current and voltage at resonce is: |
0
<span style="color: rgb(34, 34, 34); font-family: arial, sans-serif; font-size: 16px;">π</span>
-<span style="color: rgb(34, 34, 34); font-family: arial, sans-serif; font-size: 16px;">π</span>
<span style="color: rgb(34, 34, 34); font-family: arial, sans-serif; font-size: 16px;">π/2</span>
|
| 8 |
In AC system we generate sine wave form because: |
It san be easily draw
It produces least disturbance in electrical circuits
It is nature standard
Other waves cannot be produced easily
|
| 9 |
In an LRC circiut, the capacitance is made one-fourth, when an resonance . Then what should be change in inductance, so that the circuit remain in resonance? |
4 times
1/4 times
8 times
2 times
|
| 10 |
In chopke coil the resistance XL an resistance R are: |
X<sub>L</sub>=R
X<sub>L</sub><<R
X<sub>L</sub>>>R
X<sub>L</sub>=<span style="color: rgb(34, 34, 34); font-family: arial, sans-serif; font-size: 16px;">∞</span>
|
| 11 |
The peak value of alternating current is 5√2 A. The mean square value of current will be: |
5A
2.5A
5<b style="color: rgb(34, 34, 34); font-family: arial, sans-serif; font-size: 16px;">√2A</b>
5<sup>2</sup>
|
| 12 |
The peak value of alternating current is 5√2 A. The mean square value of current will be: |
5A
2.5A
5<b style="color: rgb(34, 34, 34); font-family: arial, sans-serif; font-size: 16px;">√2A</b>
5<sup>2</sup>
|
| 13 |
A capacitor is perfectly insulator for: |
Direct current
Alternating current
Direct as well as alternating current
None of these
|
| 14 |
The AC system is preferred to DC system because: |
AC voltage can be easily changed in magnitude
DC motor angular velocity is affected badly
High voltage AC transmission is less efficient
Domestic appliance require AC voltage for their operation
|
| 15 |
Eddy current is produced when: |
A metal is light in varying magnetic field
A metal is kept in steady magnetic field
A circular coil is placed in a steady magnetic field
A current is passed through a circualr coil
|
| 16 |
Step up transfer has a transformation ratio of 3:2. What is the voltage in secondary , If voltage in primary is 30 V? |
45 V
15 V
90 V
300 V
|
| 17 |
Which of the following quantities remain constant in step up transformer? |
Current
Voltage
Power
Heat
|
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