Which one of the following does not depend on the magnetic effect of current for its working:

Which one of the following does not depend on the magnetic effect of current for its working:

مندرجہ ذیل میں سے کون سا اس کے کام کرنے کے لیے کرنٹ کے مقناطیسی اثر پر منحصر نہیں ہے
Explanation

Carbon Microphone is a type of microphone, a transducer that converts sound to an electrical audio signal.

ND06-08-2023