Final answer:
To measure electrical currents in a diagram like Figure 21.47, an ammeter must be placed in series either with the entire circuit for total current or with each resistor to measure individual currents. Positioning depends on whether the resistors are aligned in series or parallel.
Step-by-step explanation:
To measure currents in a circuit diagram such as Figure 21.47, an ammeter should be strategically placed to capture the flow of current through the entire circuit or through individual resistors. To measure the total current, the ammeter needs to be placed in series with the entire circuit, just after the power source, assuming the components are configured in series. For measuring the current through individual resistors (R1, R2, R3), the ammeter should be placed in series with each respective resistor.
When connecting an ammeter, it is essential to disconnect the circuit and place the ammeter where the wire was to measure the current through that section. For more than one right answer in a parallel circuit, the ammeter can be connected in series with individual branches to measure current through specific resistors (R1, R2, R3).