Thursday, 19 June 2014 16:02

## H1-44: ULTRASONIC MOTION DETECTOR WAVE FORM

• ID Code: H1-44
• Purpose: Show the wave form of the ultrasonic signal created by the ultrasonic motion detector.
• Description: A microphone is used to pick up the signal from the ultrasonic motion detector; that signal is then amplified and viewed using an oscilloscope. The wave form consists of bursts of 45 kHz ultrasound at intervals of about 25 milliseconds. Above is the signal seen by the oscilloscope with the horizontal scale at 10 ms/division (left) and at 100 microseconds per division (right).

A question for students: Why do motion detectors use such high frequencies?

• Availability: Available
• #### H1-01 BELL IN VACUUM

Demonstrates sound wave requirement for a medium Read More
• #### H1-02 SPEAKER AND CANDLE

Demonstrates longitudinal behavior of sound waves Read More
• #### H1-03: BELLS

Use bells as a sound source Read More
• #### H1-04: BELL IN VACUUM - PORTABLE

Small version of the standard bell in vacuum demonstration Read More
• #### H1-11: MICROPHONE AND OSCILLOSCOPE

Show the wave shape of various sounds Read More
• #### H1-12: VISIBLE WAVEFORMS ON LARGE SPEAKER

Show the loudspeaker motion produced by waves of various shapes Read More
• #### H1-13 WAVEFORM GENERATOR, SPEAKER AND OSCILLOSCOPE

Demonstrates waveform and sound of standard waves Read More
• #### H1-21: SPEED OF SOUND - PHASE CHANGE

Determine the speed of sound Read More
• #### H1-22: SPEED OF SOUND - USING PULSES

Determine the speed of sound in air Read More
• #### H1-24: SPEED OF SOUND IN HELIUM

Determine the speed of sound as a function of gas density Read More
• #### H1-25: SPEED OF SOUND BETWEEN TWO MICROPHONES

Measure the speed of sound by determining the travel time of a pulse between two microphones Read More
• #### H1-26: SPEED OF SOUND IN GARDEN HOSE

Direct measurement of the speed of sound in air Read More
• #### H1-27: SPEED OF SOUND - LISSAJOUS FIGURES

Measurement of the speed of sound in air using Lissajous figures Read More
• #### H1-31: SOUND LEVEL METER

Demonstrate use of a sound level meter Read More
• #### H1-32: WAVETEK AND AUDIO CART - EQUAL SOUND LEVEL STEPS

Illustrate the effect on the ear of successive changes of exactly 10 dB Read More
• #### H1-41: ULTRASONIC MOTION DETECTOR

Demonstrate how an ultrasonic motion detector works Read More
• #### H1-43: ULTRASONICS AND HEARING

Demonstrate that there exist ultrasonic waves with frequencies above the range of human hearing Read More
• #### H1-44: ULTRASONIC MOTION DETECTOR WAVE FORM

Show the wave form of the ultrasonic signal created by the ultrasonic motion detector Read More
• #### H1-51: AUDIOTAPE 42 MIN - SCIENCE OF SOUND - SHORT VERSION

Illustrate various audio phenomena Read More
• #### H1-52: AUDIOTAPE 82 MIN - SCIENCE OF SOUND - LONG VERSION

Illustrate various audio phenomena Read More