The Lissajous pattern observed on screen of CRO is a straight line inclined at 4

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Question
The Lissajous pattern observed on screen of CRO is a straight line inclined at 45� to x axis. If X-plate input is 2 sin ?t, the Y-plate input is
Options
A. 2 sin ?t
B. 2 sin (?t + 45�)
C. 2 sin (?t - 45�)
D. 22 sin ?t + 45�)

Correct Answer

2 sin ?t

Explanation

When signals to X and Y plates are in phase, the display is a straight line inclined at 45�.

Measurements and Instrumentation problems

Search Results

1. To increase Q factor of a coil, the wire should be
Options
A. long
B. thin
C. thick
D. long and thin

2. A standard cell of 1.0185 V is used with a slide wire potentiometer. The balance was obtained at 60 cm. When an unknown emf was connected, the balance was obtained at 82 cm. The magnitude of unknown emf is
Options
A. 1.39 V
B. 0.75 V
C. 13.9 V
D. 7.45 V

5. In two wattmeter method of 3 phase power measurement, when does one wattmeter read negative
Options
A. when power factor is less than 0.5 lagging
B. when power factor is greater than 0.5 lagging
C. when power factor is less than 0.5
D. when power factor is unity

6. The angle ? for a mica capacitor is about
Options
A. 25�
B. 15�
C. 5�
D. 1�

7. A voltmeter using thermocouples measures
Options
A. rms value
B. peak value
C. average value
D. peak to peak value

8. Which of the following statement is correct for two wattmeters method of power measurement in 3 phase circuit?
Options
A. Power can be measured by this method only for star connected loads
B. When two wattmeters have equal readings power factor is 0.5.
C. When power factor is 1, one of the wattmeters readings is zero
D. When the two wattmeter read equal and opposite, p.f. is zero.

9. In a CRO which of the following is not a part of electron gun
Options
A. cathode
B. grid
C. accelerating anode
D. X - Y plates

10. The coil of a moving iron instrument has a resistance of 500 ? and an inductance of 1 H. It reads 250 V when a 250 V dc is applied. If series resistance is 2000 ?, its reading when fed by 250 V, 50 Hz ac will be
Options
A. 260 V
B. 252 V
C. 250 V
D. 248 V

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