Adjusting CRO for One Wave Cycle

Steps:

• Determine the waveform's period (time for one cycle) from the sound frequency.
• Increase time base to slow horizontal sweep, expanding the trace to fit exactly one cycle across the screen.
• Assess vertical amplitude; if trace is small, increase y-gain to amplify deflection and fill the screen height.
• Verify sinusoidal shape emerges clearly without distortion.

Why D is correct:

• Increasing time base (s/cm) stretches the horizontal axis per CRO definition, displaying one period; increasing y-gain (V/cm) scales amplitude upward for full visibility.

Why the others are wrong:

• A: Decreasing time base compresses time, showing multiple cycles instead of one.
• B: Increasing time base helps period but decreasing y-gain shrinks amplitude, making trace too small.
• C: Decreasing both compresses time and shrinks amplitude, worsening the display.

Final answer: D