An engineer designs an autonomous telemetry system for a marine monitoring buoy. The schematic diagram of the internal circuitry is shown below.
The battery pack has an internal resistance of 2.4 Ω2.4\ \Omega2.4 Ω.
Show that the resistance of the 10.8 V,7.2 W10.8\text{ V}, 7.2\text{ W}10.8 V,7.2 W telemetry transmitter at its working potential difference (pd) is 16.2 Ω16.2\ \Omega16.2 Ω.
When the telemetry transmitter is operating at its working pd, the terminal pd across the battery pack is 10.8 V10.8\text{ V}10.8 V. Calculate the electromotive force (emf) of the battery pack. Give your answer to 3 significant figures.
A technician designs a variable power-limiting control for a different circuit using a length of resistance wire with a diameter of 0.36 mm0.36\text{ mm}0.36 mm. An 8.5 m8.5\text{ m}8.5 m length of this wire has a resistance of 15.0 Ω15.0\ \Omega15.0 Ω. Calculate the resistivity of the material from which the wire is made.