Final answer:
Ultrasound diathermy is the medium frequency AC where the interference between 2 different frequencies from separate channels is used for pain relief. It uses high-intensity ultrasound with frequencies of 0.8 to 1 MHz to treat injured or overworked muscles.
Step-by-step explanation:
The medium frequency AC where the interference between 2 different frequencies from separate channels is used for pain relief is called ultrasound diathermy.
Ultrasound diathermy is a form of therapy that uses high-intensity ultrasound with frequencies typically ranging from 0.8 to 1 MHz. It is commonly used in physical therapy and athletics to relieve pain and improve flexibility in injured or overworked muscles.
To avoid tissue damage and overheating, skill is needed by the therapist to ensure safe and effective treatment.