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Ultrasound and Infrasound
Infrasound <20 Hz; ultrasound >20 kHz.
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Ultrasound and Infrasound
Recommended for Class 10
Ultrasound and Infrasound
Human hearing covers only a limited frequency range.
For a young healthy person, the commonly quoted approximate range is:
20 Hz to 20,000 Hz
Infrasound
Sound with frequency below about 20 Hz is called infrasound.
Humans normally cannot hear it.
It can be produced by:
earthquakes; volcanoes; large machines; some animals.
Ultrasound
Sound above about 20 kHz is called ultrasound.
Humans normally cannot hear it.
Uses of Ultrasound
medical imaging; sonar; industrial flaw detection; cleaning; * distance measurement.
Medical Ultrasound
High-frequency sound pulses enter the body and reflect from boundaries between different tissues.
The returning echoes are processed to produce images.
Ultrasound and Infrasound — Advanced
Common Mistakes
Common Mistakes
- Mistake
Ultrasound is still sound, not electromagnetic radiation.
- Mistake
“Inaudible” does not mean no energy.
- Mistake
Hearing range varies among individuals and with age.
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Practice
PQ
Q1. Define ultrasound.
PQ
Q2. Define infrasound.
PQ
Q3. State human hearing range.
PQ
Q4. Give two uses of ultrasound.
PQ
Q5. Explain medical ultrasound imaging.
Exam Practice
EQ
Q1. Define ultrasound.
EQ
Q2. Define infrasound.
EQ
Q3. State human hearing range.
EQ
Q4. Give two uses of ultrasound.
EQ
Q5. Explain medical ultrasound imaging.
School-standard facts for Matric and Intermediate. Original explanations — not copied from textbooks.