Question

Tungsten metal is used to make a solenoid-type coil in an electric bulb.

Hint:

Tungsten is ideal for electric bulbs because it has a high melting point (\(3422^\circ C\)) and emits visible light efficiently when heated. The coiled filament structure maximizes brightness and durability.

Answer 1

Step 1: Understanding the choice of tungsten
- Tungsten (\(\text{W}\)) is a metal with a very high melting point of approximately 3422°C. - When an electric current passes through tungsten, it gets heated to high temperatures and emits visible light.
Step 2: Why tungsten is used in the form of a solenoid-type coil
- The filament inside an electric bulb is a coiled tungsten wire. - The coil shape: - Increases the length of the wire, allowing more resistance. - Concentrates heat, increasing efficiency. - Reduces heat loss, ensuring it remains at high temperatures to emit bright light.
Step 3: Properties making tungsten ideal for bulbs
- High melting point: Prevents it from melting under extreme heat. - High resistivity: Converts electrical energy into heat effectively. - Low evaporation rate: Ensures durability inside the vacuum/sealed gas bulb. Thus, tungsten is used in electric bulbs due to its high melting point, resistivity, and efficient light emission.