|
Frequency of ultrasonic wavesis |
|||
|
(a) |
less than 20000 Hz |
(b) |
greater than 20000 Hz |
|
(c) |
less than 20 Hz |
(d) |
1000 Hz |
|
Frequency of ultrasonic wavesis |
|||
|
(a) |
less than 20000 Hz |
(b) |
greater than 20000 Hz |
|
(c) |
less than 20 Hz |
(d) |
1000 Hz |