The drift velocity of an electron is of the order 10^-4 m/sec but then also while switching on any light bulb, why does it starts to glow immediately?

Question

Answer

Why does a light bulb glow immediately when switched on even though the drift velocity of electrons is very low?

When a light bulb is switched on, it starts to glow immediately despite the fact that the drift velocity of electrons is very low. This is because the current that flows through the bulb is not due to the drift of electrons, but due to the movement of free electrons, called conduction electrons, in the metal wire. These electrons move at a much faster speed than the drift velocity of electrons.

Conduction Electrons

Conduction electrons are free electrons that are not bound to any particular atom. In a metal wire, there are many conduction electrons that are free to move around. When a voltage is applied to the wire, these electrons start to move in the direction of the electric field. This movement of electrons creates a flow of current in the wire.

Electric Field

When a voltage is applied to a wire, it creates an electric field in the wire. This electric field exerts a force on the conduction electrons, causing them to move in the direction of the electric field. The strength of the electric field depends on the voltage applied and the resistance of the wire.

Resistance

Resistance is the property of a material that opposes the flow of current through it. In a wire, resistance is caused by collisions between the conduction electrons and the atoms of the wire. These collisions slow down the movement of the electrons and create a resistance to the flow of current.

Conclusion

In conclusion, the drift velocity of electrons is very low, but the movement of conduction electrons in a wire is much faster. This movement of electrons creates a flow of current in the wire, which causes the light bulb to glow immediately when it is switched on.

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