A lantern uses a single rechargeable battery whose emf is 6.00V and whose internal resistance is 0.40Ω. The bulb inside the lantern can be modeled as a 20.0Ω resistor that remains at constant resistance while operating.
(1) Part 1: Calculate the current delivered to the bulb while the lantern is on.
(2) Part 2: Determine the terminal potential difference across the battery while the lantern is operating.
(3) Part 3: Compute the power dissipated internally within the battery and compare it to the power delivered to the bulb.
(4) Part 4: Express the efficiency of the energy transfer from the battery to the bulb as a percentage, where efficiency is defined as (power to bulb)/(total power produced by the battery).