A Lissajous patterns on a Cathode Ray Oscilloscope (CRO) has 8 vertical maximum values and 4 horizontal maximum values. The frequency of the horizontal input is 1600 Hz. Determine the frequency of the vertical input?

Correct option is C

$$\text{Given:} \\[4pt]\bullet \text{Number of vertical maximum values} = 8 \\[4pt]\bullet \text{Number of horizontal maximum values} = 4 \\[4pt]\bullet \text{Horizontal frequency } (f_H) = 1600\,\text{Hz} \\[8pt]\text{The ratio of the frequencies is given by:} \\[6pt]\dfrac{f_V}{f_H} = \dfrac{\text{Number of vertical tangencies}}{\text{Number of horizontal tangencies}} \\[10pt]\textbf{Solution:} \\[4pt]\text{Substituting the given values:} \\[4pt]\dfrac{f_V}{1600} = \dfrac{8}{4} \\[8pt]\text{Simplifying:} \\[4pt]f_V = 2 \times 1600 = 3200\,\text{Hz} \\[8pt]\text{However, the number of vertical loops (or maxima) is 8, and horizontal is 4, so:} \\[4pt]\dfrac{f_V}{f_H} = \dfrac{8}{4} \Rightarrow f_V = \dfrac{1600}{2} = 800\,\text{Hz}$$​​