Question

The horizontal plates of CRO is supplied with following to observe the waveform

• A. Sine wave
• B. Cos wave
• C. Sawtooth wave
• D. Square wave

Hint:

Sawtooth wave provides linear time sweep in CRO.

Answer 1

The Correct Option is C

Step 1: State the requirement for the horizontal deflection.
The horizontal plates of a CRO deflect the electron beam along the time axis. To display a waveform correctly, the beam must move from left to right at a constant, uniform speed.

Step 2: Identify which waveform provides linear motion.
A sawtooth wave rises linearly from its minimum to its maximum over the sweep period $T$. This linear rise produces a constant deflection rate -- the beam moves at steady speed. At the end of $T$, the waveform drops instantly (flyback), returning the beam to the left.

Step 3: Eliminate other options.
A sine wave produces non-linear horizontal motion: the beam moves fastest near zero crossings and slowest near peaks, distorting the time axis. Only the sawtooth provides a linear time base. \[ \boxed{\text{Sawtooth wave}} \]