Physics Lab Equipment

LEMI-51 Interference, Diffraction and Speed Measurement of Sound Wave

LEMI-51 Interference, Diffraction and Speed Measurement of Sound Wave

Note: oscilloscope not included 


  • High performance ultrasonic sensor

  • Simple structure, stable and reliable

  • Multiple experiments


The measurements of many physical parameters such as ultrasonic distance, positioning, liquid flow, elastic modulus of materials, and gas temperature transient changes, involve sound speed. This apparatus is specially designed to observe standing waves and resonance phenomenon of interference, measure the speed and wavelength of sound in air, observe double-slit interference and diffraction of sound, and observe the interference of original wave and reflected wave. Through the experiments, students can have a better understanding of the fundamentals of acoustic wave and related experimental methods.


This apparatus is designed with the following characteristics:


1. An ultrasonic sensor with strong anti-interference capability to ensure high performance operation

2. Ultrasonic receiver in connection to a rotating device to measure rotational angles

3. A reflective plate to conduct interference experiment between reflected wave and original wave


Using this apparatus, the following experiments can be conducted:


1. Generate and receive ultrasound

2. Measure sound speed in air using phase and resonance interference methods

3. Study the interference of reflected and original sound wave, i.e. sound wave "LLoyd mirror" experiment

4. Observe and measure double-slit interference and single-slit diffraction of sound wave

The instruction manual contains experimental configurations, principles, step-by-step instructions, and examples of experiment results. Please click Experiment Theory and Contents to find more information about this apparatus.

Parts and Specifications

Sine wave signal generatorFrequency range: 38 ~ 42 kHz; resolution: 1 Hz
Ultrasonic transducerPiezo-ceramic chip; oscillation frequency: 40.1 ± 0.4 kHz
Vernier caliperRange: 0 ~ 200 mm; accuracy: 0.02 mm
Ultrasonic receiverRotational range: -90° ~ 90°; unilateral scale: 0° ~ 20°; division: 1°
Measurement accuracy<2% for phase method

LEMI-51 Sound Wave-1.jpg

1. power switch

2. displacement display

3. display reset

4. displacement knob

5. signal input

6. emitter

7. receiver

8. signal output

9. rotation guide

LEMI-51 Sound Wave-2.jpg

Double-slit interference

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