If the horizontal input is Em sin(ωt) V and vertical input is Em sin (ωt + \(50^\circ\)) V, then what will be the Lissajous pattern on CRO?

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PGCIL DT Electrical 5 May 2023 Official Paper
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  1. F3 Vinanti Engineering 21.09.23 D13
  2. F3 Vinanti Engineering 21.09.23 D14
  3. F3 Vinanti Engineering 21.09.23 D15
  4. F3 Vinanti Engineering 21.09.23 D16

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Option 3 : F3 Vinanti Engineering 21.09.23 D15
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Concept:

When two sinusoidal signals of the same frequency and magnitude are applied two both pairs of deflecting plates of CRO, the Lissajous pattern changes with the change of phase difference between signals applied to the CRO

When 0 < ϕ < 90o or 270o < ϕ < 360o 

The Lissajous pattern is of the shape of an Ellipse having a major axis passing through the origin from the first quadrant to the third quadrant.

 When 90o < ø < 180o or 180o < ø < 270o

The Lissajous Pattern is of the shape of an Ellipse having a major axis passing through the origin from the second quadrant to the fourth quadrant.

Explanation:

The given inputs are: Em sin (ωt) V, Em sin (ωt + 50°) V

The phase difference between both the inputs = 50°

The Lissajous pattern on the screen of a CRO is an ellipse with a major axis in quadrant 1 and quadrant 3. 

Additional Information 

F2 Savita ENG 18-9-24 D1 V2

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