This question asks us to determine the frequency of a sinusoidal signal displayed on a Cathode Ray Oscilloscope (CRO). We are given information about how the signal appears horizontally on the screen and the CRO's time base setting. The vertical information is not needed to calculate the frequency.

CRO Horizontal Measurement

The horizontal axis of a CRO represents time. The display is divided into divisions, and the 'time base' setting tells us how much time each horizontal division represents. To find the frequency of a signal, we first need to determine the time period of one complete cycle of the waveform.

Calculating the Time Period (T)

Here's how we can find the time period of the signal:

• Horizontal Divisions for One Cycle: The question states that one complete cycle of the sinusoidal signal occupies five horizontal divisions.
• Time Base Setting: The time base is set to 1 ms per division.
• Total Time Period Calculation: The total time period ($T$) is the product of the number of horizontal divisions occupied by one cycle and the time base setting. $$ T = (\text{Number of horizontal divisions for one cycle}) \times (\text{Time base setting per division}) $$ Plugging in the values: $$ T = 5 \text{ divisions} \times 1 \text{ ms/division} $$ $$ T = 5 \text{ ms} $$

Converting Time Period to Seconds

For frequency calculations, the time period needs to be in seconds. We know that 1 millisecond (ms) is equal to $1 \times 10^{-3}$ seconds.

So, the time period in seconds is:

$$ T = 5 \text{ ms} = 5 \times 10^{-3} \text{ s} $$

Calculating Signal Frequency (f)

Frequency ($f$) is the reciprocal of the time period ($T$). The formula is:

$$ f = \frac{1}{T} $$

Now, we substitute the value of the time period in seconds:

$$ f = \frac{1}{5 \times 10^{-3} \text{ s}} $$

To calculate this:

$$ f = \frac{1000}{5} \text{ Hz} $$ $$ f = 200 \text{ Hz} $$

Therefore, the frequency of the sinusoidal signal is 200 Hz.