Wave - Catode-ray Oscillatione CRO

Cathode-ray Oscilloscope (CRO)

Oscilloscope

​Measuring frequency

You can measure the frequency of sound waves using a cathode-ray oscilloscope (CRO) or oscilloscope for short

Worked Example

this picture shows the trace on an oscilloscope screen when sound waves are detected by a microphone.
The time-base is set at 1 ms div⁻¹. The y-gain is set to 20 mV div⁻¹.

Determine the frequency of the sound waves and the amplitude of the oscilloscope trace

Worked Example

​The time-base is set at 1 ms div⁻¹

Worked Example

Find Amplitude :
A = 3.5 div
A = 3.5 x 20 mV
A = 70 mV
A = 70 x 10^-3 V
A = 0.07 V

​The y-gain is set to 20 mV div⁻¹

Multiple Choice

A sound wave is displayed on the screen of a cathode-ray oscilloscope, as shown. The time-base setting is 0.50 ms per division. What is the frequency of the sound wave?

• 670 Hz

• 570 Hz

• 470 Hz

• 370 Hz

Multiple Choice

A cathode-ray oscilloscope (CRO) is used to display the trace from a sound wave. The time-base is set at 5µs cm^–1. What is the frequency of the sound wave?

• 6.7 Hz

• 67 Hz

• 6.7 kHz

• 67 kHz

Multiple Choice

A cathode-ray oscilloscope (CRO) is used to determine the frequency of a sound wave. The diagram shows the waveform on the screen. The time-base setting is 5.0 ms div–1. What is the best estimate of the frequency of the sound wave?

• 50 Hz

• 71 Hz

• 100 Hz

• 143 Hz

Multiple Choice

A cathode-ray oscilloscope displays a square wave, as shown. The time-base setting is 0.20 ms per division. What is the frequency of the square wave?

• 0.83 Hz

• 83 Hz

• 830 Hz

• 8300 Hz

Multiple Choice

A sound wave is detected by a microphone and displayed on the screen of a cathode-ray oscilloscope (CRO). The frequency of the wave is 2.5 kHz. What is the setting on the time-base of the CRO?

• 0.1 ms cm^–1

• 0.4 ms cm^–1

• 0.1 s cm^–1

• 0.4 s cm^–1

Multiple Choice

A sound wave of frequency 270 Hz is recorded by a cathode-ray oscilloscope (CRO). The waveform on the CRO is shown. What is the time-base setting on the CRO?

• 0.1 mscm^-1

• 1 mscm^-1

• 10 mscm^-1

• 100 mscm^-1

Multiple Choice

The diagram shows a representation of a wave on the screen of an oscilloscope. The y-gain is set to 3.5 mVcm^–1. What is the amplitude of the wave?

• 0.57 mV

• 3.5 mV

• 7.0 mV

• 14 mV