Explain how metallic and mercury thermometers work.

Here's how metallic and mercury thermometers work:

• Metallic Thermometer: These thermometers typically use a bimetallic strip, which is made of two different metals bonded together. Each metal expands at a different rate when heated. This difference in expansion causes the strip to bend or coil. This mechanical movement is then linked to a pointer that moves across a calibrated scale, indicating the temperature.

• Mercury Thermometer: This type of thermometer operates on the principle of thermal expansion of mercury. A reservoir (bulb) at the bottom contains mercury, which is connected to a very narrow glass tube called a capillary. When the thermometer is exposed to heat, the mercury expands and rises up the capillary tube. The height of the mercury column against a marked scale on the glass indicates the temperature.