Match List I with List II:
| List I | List II | ||
|---|---|---|---|
| A. | <20 Hz | I. | Longitudinal waves |
| B. | >20000 Hz | II. | Electromagnetic waves |
| C. | X-rays | III. | Infrasonic waves |
| D. | Sound waves | IV. | Ultrasonic waves |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → A-III, B-IV, C-II, D-I
The human ear hears sound of frequencies from about 20 Hz to 20,000 Hz; sound below and above this range has its own name.
A. <20 Hz — this matches III. Infrasonic waves. Sound below 20 Hz is too low to hear; elephants and whales use it, and earthquakes produce it.
B. >20000 Hz — this matches IV. Ultrasonic waves. Sound above 20,000 Hz is too high to hear; bats and dolphins use it, and it is used in medical scans and SONAR.
C. X-rays — this matches II. Electromagnetic waves. X-rays are light-like waves of very short wavelength and need no medium.
D. Sound waves — this matches I. Longitudinal waves. In air, the particles of the medium move back and forth along the direction in which the sound travels.