A mobile phone charger provides a constant output of 5.0V. The connecting USB cable has a resistance of 180mΩ and must carry a steady current of 2.0A when the phone is charging.
(i) Calculate the potential difference lost (voltage drop) across the cable.
(ii) Determine the voltage actually available at the phone’s terminals during charging.
(iii) To ensure that the terminal voltage never falls below 4.9V for the same charging current, compute the maximum allowable resistance of the cable. Give your answer in milliohms.