Automobile Headlight Circuit

Here is how the circuit works:

  1. Chemical interactions and forces in the battery cause electrical charges to flow through the circuit.

  2. The wires are made of conductors (for example, copper) and are insulated from each other by electrical insulation (plastic) coating the wires.

  3. Insulators are materials that resist the flow of current.

  4. Charges flow through the conductor but not through the plastic insulation.

  5. The switch is used to control the flow of current.

  6. When the conducting metallic parts of the switch make contact, we say the switch is closed and the current flows through the electric circuit.

  7. In contrast, when the conducting parts of the switch do not make contact, we say that the switch is open and current does not flow.

The headlamps contain special tungsten wires. Here are some characteristics of the tungsten wires:

  • They can withstand high temperatures.

  • Tungsten is not an electrical conductor as good as copper, and the charges experience collisions with the atoms of the tungsten wires, resulting in heating of the tungsten.

  • We say that the tungsten wires have electrical resistance when they exhibit a certain resistance to the flow of current.

  • The tungsten becomes hot enough so that copious light is emitted.

We will see in the coming sections that the power transferred to the headlamp is equal to the product of current (rate of flow of charge) and the voltage applied by the battery.
               

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