When an electrical appliance is switched on or off, electricity does not flow through the wires instantaneously due to several factors related to the electrical circuit's behavior:
Capacitance: In electrical circuits, capacitors are components that can store electrical charge. Many electrical devices, especially those with electronic components, contain capacitors. When an appliance is switched off, the capacitors may hold a residual charge, preventing immediate current flow when the switch is turned on. It takes a brief moment for this charge to dissipate, allowing current to flow through the circuit.
Inductance: Inductors are components that store energy in a magnetic field. In some circuits, especially those with coils or transformers, inductance can cause a momentary delay in the flow of current when an appliance is switched on or off. This delay is often very short but can be noticeable in certain situations.
Switching time: Mechanical switches and relays take a finite amount of time to make or break the electrical connection. This is known as the switching time. While modern switches and relays are designed for fast operation, there is still a brief moment of delay between the switch's physical movement and the establishment or interruption of the electrical path.
Rise time and settling time: In more complex electronic circuits, there are phenomena like rise time and settling time associated with various components and signals. These phenomena contribute to the delay in establishing a steady flow of current when an appliance is switched on or off.
Circuit complexity: The internal circuitry of electrical appliances can be quite intricate, especially in modern electronics. There can be various safety features, control mechanisms, and processing units that need a fraction of a second to initialize when the appliance is powered on.
Overall, these factors combined create a brief delay in the flow of electricity when an appliance is switched on or off. In most cases, this delay is negligible and not noticeable to the user. However, in certain situations or with more complex electronic devices, it may be perceivable as a small pause before the appliance starts operating or fully shuts down.