The primary coil of a step-down transformer on a marine research station has 100010001000 turns, and its secondary coil has 404040 turns. An alternating voltage supply is connected across the primary coil. A diagnostic transmitter that dissipates 80 W80\text{ W}80 W at its operating potential difference of 16 V16\text{ V}16 V is connected across the secondary coil. The transformer is 100%100\%100% efficient.
Calculate the current in the primary coil during normal operation of the transmitter.
The alternating voltage supply is replaced by a 24 V24\text{ V}24 V DC battery pack and an open mechanical switch in series. The switch is closed. Explain why the transmitter is only powered briefly at the instant of switch closure and then remains off.
