Final answer:
Pushing a normally open pushbutton in a low-voltage system closes the circuit, allowing current to flow from a 24 V supply to a transformer, stepping up the voltage to 120 V for a load. When open, the switch prevents current flow; when closed, it allows current to energize connected devices.
Step-by-step explanation:
Understanding the Role of Switches in Electrical Circuits
A normally open pushbutton is a type of switch that, when unengaged, has an extremely large resistance, effectively breaking the circuit and preventing electrical current from flowing. However, when the pushbutton is pressed, its resistance drops to nearly zero, allowing current to flow through the circuit. Consequently, pushing a normally open pushbutton in a low-voltage switching system will complete the circuit and allow current to flow from the 24 V supply, subsequently energizing the relay coil and enabling the supply of 24 V to a transformer. This transformer can step-up the voltage to 120 V to power a load, which is the typical scenario in basic electrical systems.
The effect of the switch on current flow is straightforward. When the switch is open, current flow is interrupted due to the high resistance, which results in no energy being transferred. When closed, the switch presents minimal resistance, facilitating current to move through and energize the connected devices, such as a relay coil in a controlling mechanism. The current allows the relay to actuate, change contacts, and switch connected electrical loads.
In high-current situations, a large current flow may cause a notable voltage drop across the circuit's resistance elements. This can impact the performance of other devices sharing the same power source, causing, for example, lights to dim when a high-power appliance is turned on.