The GATE Grind

GATE 2026 IN – Question 48

Measurements · Time frequency and instruments · 2 marks · Multiple choice

A closed Lissajous pattern observed on an oscilloscope in X–Y mode has three horizontal tangencies and two vertical tangencies in steady state. If the signal frequency on channel X is 600 Hz, then the signal frequency on channel Y is ________ Hz.

  1. 300
  2. 400
  3. 600
  4. 900

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Correct answer: (D) 900

Explanation

For the closed pattern, the ratio of horizontal to vertical tangencies gives $f_Y/f_X=3/2$.

Thus $f_Y=(3/2)(600)=900\ \mathrm{Hz}$, **D**.