Fifteen seconds after closing the control switch, what will the red light indicate if Sw 1 has been closed for 30 minutes?

When evaluating the situation where Sw 1 has been closed for 30 minutes, it's important to consider how control switches typically function in electrical circuits. If the switch has been continuously closed for an extended period, in this case, 30 minutes, it generally means that power has continuously been supplied to the circuit.

After an additional 15 seconds following the closure of the control switch, the red light will indicate ON. This is because the light is likely designed to remain illuminated as long as it is receiving power from the closed switch. The nature of control systems often dictates that a light will stay lit under normal operation until the circuit is interrupted or the switch is opened.

In scenarios where the red light is OFF, flashing, or dim, specific conditions would need to occur, such as the switch being opened, a malfunction within the circuit, or a design feature intended to signal different statuses. However, since the switch in this case remains closed continuously, these alternatives do not apply. Thus, the red light will reliably indicate ON due to the continued power supply.