Question 217Electricity & Electronics - Assistant Engineer

The correct answer is D) each station's hand-cranked generator. Sound-powered telephones do not require external power sources to operate the small vibrating bells. Instead, they utilize the mechanical energy generated by the user cranking a small hand-operated generator at each station to produce the necessary electrical energy to power the bell. This self-contained power source is a key design feature of sound-powered telephone systems, allowing them to function independently without relying on the ship's main electrical system. The other options are incorrect because they do not accurately describe the power source for sound-powered telephone bells. The emergency batteries, normal 115V DC supplies, and emergency switchboard are not involved in powering these specialized telephone systems.