Lissajous pattern obtained on a CRO screen is a circle. Frequency of two signals are

Lissajous pattern:

• When the pair of deflection plates (horizontal and vertical) of CRO is connected to two sinusoidal voltages, then the pattern that appears on the CRO screen is called the Lissajous pattern.
• The shape of these Lissajous pattern changes with the change of phase difference between signals and ratio of frequencies applied to the deflection plates of CRO.
• These patterns very useful in analyzing the signals applied to deflection plates of CRO.

Application of Lissajous pattern:

• To calculate the phase difference between two sinusoidal signals having the same frequency.
• To determine the ratio of frequencies of sinusoidal signals applied to the vertical and horizontal deflecting plates.

For different values of phase differences, the shape of Lissajous patterns is shown in the figure below,

Hence, Lissajous pattern obtained on a CRO screen is a circle. Frequency of two signals are equal.