Final answer:
The meter reading in a charging system depicts the charging circuit voltage drop. This is determined by the current measured by the ammeter in series and the internal resistance of the battery, allowing calculation of the terminal voltage during charging.
Step-by-step explanation:
In the context of the charging system described, the meter reading will show the charging circuit voltage drop. This is because an ammeter is used to measure the current flowing through a circuit and is always placed in series. The voltage drop across any component in a series circuit can be calculated if we know the current through the circuit and the resistance of the component. In a charging system for a battery, the internal resistance of the battery will cause a voltage drop which is in addition to the electromotive force (emf) of the battery when charging current is flowing.
Considering a car battery with a 12-V emf and an internal resistance of 0.050Ω being charged with a current of 60 A, the potential difference across its terminals can be calculated with Ohm's Law (V = IR). Thus, terminal voltage is the emf minus the product of the charging current and the internal resistance (12 V - (60 A * 0.050Ω)). The output voltage of the battery charger must be higher than the terminal voltage to facilitate charging.