Choose a frequency of 400 Hz and a source velocity of 2 m/s (4.5 mph). Observe and record the frequencies as the speaker moves toward you and then away from you.

1. If the switch is closed, the total resistance of the circuit remains the same

2. The brightness of the bulb A when the switch is closed remains the same.

Explanation:

An ideal battery has no internal resistance, and hence, maintains a constant value of voltage without diminishing. The total resistance of the circuit will remain constant since this is an inherent unchanging property of a conducting circuit provided there is no change to its configurations. The brightness of the bulb A will remain unchanged since we are considering an ideal battery. In practice, ideal batteries don't exist, reason why battery powered light bulbs gradually dim with time as the internal resistance increases, till it eventually dies.