State ‘magnetostriction effect’. Mention any two application of ultrasonic waves
When a ferromagnetic rod is placed along a magnetic field it undergoes a small change in it length. If the steady magnetic field is replaced by an alternating magnetic field it undergoes
alternate extension and contraction. If the frequency of the alternating magnetic field is high the
rod starts vibrating exhibiting longitudinal vibrations. When the frequency of the applied field is high the rod produces ultrasonic waves in the surrounding medium.
Acoustic transducer : SONAR, Hydrophone, ultrasonic cleamimg, ultrasonic friction welding.
Actuator: pump, Active valve, Rotary motor.
Sensor: vibration sensor, position sensor, torque sensor.