Why the bulb glows when the electric current passes through it?
the filament has electrical resistance. When electricity passes through it, it generates heat -- so much heat that the wire glows.
The filament in the bulb has resistance. The current flowing through the resistance of bulb causes the filament to dissipate energy in the form of heat and light. The filament is actually glowing white-hot because of the energy it is dissipating, thus giving off light. Any object having high temperature glows.
When an electric current passes through a bulb, it glows due to a phenomenon called incandescence. Incandescence refers to the emission of light from a heated object. In the case of a light bulb, the current passes through a tungsten filament, which is a thin wire inside the bulb.
To understand why the bulb glows, we need to consider the properties of the filament and the nature of the electric current. The filament in a light bulb is made of tungsten because it has a high melting point and is very resistant to heat.
When an electrical current flows through the filament, it encounters resistance, causing the filament to heat up. As the filament heats up, it reaches a temperature high enough to emit visible light. This process is similar to how a stove burner or an incandescent lamp works.
The specific temperature at which the filament starts to glow depends on the material of the filament and the amount of current flowing through it. Tungsten filaments typically reach temperatures of around 2,500 to 3,500 degrees Celsius (4,500 to 6,300 degrees Fahrenheit) during normal operating conditions.
Once the filament reaches this high temperature, it emits light in the form of photons. These photons then pass through the transparent glass envelope of the bulb, resulting in the glow that we see.
Therefore, the essential reason why a bulb glows when an electric current passes through it is due to the heating of the tungsten filament, reaching temperatures high enough to emit visible light through a process known as incandescence.