Thermometry: Measuring Temperature

Thermometry

• Definition: Thermometry is the science of measuring temperature.
• Thermometers: Devices used to measure temperature, typically consisting of a temperature sensor and a display.
• Types of Thermometers:
  1. Mercury-in-glass thermometers: Use expansion of mercury to measure temperature.
  2. Digital thermometers: Use electronic sensors and display temperature digitally.
  3. Infrared thermometers: Measure temperature using infrared radiation.
  4. Thermocouples: Measure temperature using the Seebeck effect (voltage generated by temperature difference).

Heat Transfer

• Definition: Heat transfer is the transfer of thermal energy from one body to another due to a temperature difference.
• Modes of Heat Transfer:
  1. Conduction: Direct transfer of heat between particles in physical contact.
  2. Convection: Heat transfer through the movement of fluids (e.g., air, water).
  3. Radiation: Heat transfer through electromagnetic waves (e.g., light, radio waves).
• Heat Transfer Equations:
  1. Fourier's Law: Describes heat conduction (Q = -k * A * (dT/dx)).
  2. Newtons Law of Cooling: Describes heat convection (Q = h * A * (T_s - T_f)).

Temperature Scales

• Definition: Temperature scales are systems for measuring temperature, each with its own zero point and unit of measurement.
• Common Temperature Scales:
  1. Celsius (°C) Scale:
     • Water freezes at 0°C.
     • Water boils at 100°C.
  2. Fahrenheit (°F) Scale:
     • Water freezes at 32°F.
     • Water boils at 212°F.
  3. Kelvin (K) Scale:
     • Absolute zero (0 K) is the theoretical minimum temperature.
     • Water freezes at 273.15 K.
     • Water boils at 373.15 K.
• Temperature Conversion: °F = (°C × 9/5) + 32 °C = (°F - 32) × 5/9 K = °C + 273.15

Thermometry

• Thermometry is the science of measuring temperature.
• Thermometers are devices used to measure temperature, consisting of a temperature sensor and a display.

Types of Thermometers

• Mercury-in-glass thermometers use expansion of mercury to measure temperature.
• Digital thermometers use electronic sensors and display temperature digitally.
• Infrared thermometers measure temperature using infrared radiation.
• Thermocouples measure temperature using the Seebeck effect (voltage generated by temperature difference).

Heat Transfer

• Heat transfer is the transfer of thermal energy from one body to another due to a temperature difference.

Modes of Heat Transfer

• Conduction is the direct transfer of heat between particles in physical contact.
• Convection is heat transfer through the movement of fluids (e.g., air, water).
• Radiation is heat transfer through electromagnetic waves (e.g., light, radio waves).

Heat Transfer Equations

• Fourier's Law describes heat conduction: Q = -k * A * (dT/dx).
• Newton's Law of Cooling describes heat convection: Q = h * A * (T_s - T_f).

Temperature Scales

• Temperature scales are systems for measuring temperature, each with its own zero point and unit of measurement.

Common Temperature Scales

• Celsius (°C) Scale:
  • Water freezes at 0°C.
  • Water boils at 100°C.
• Fahrenheit (°F) Scale:
  • Water freezes at 32°F.
  • Water boils at 212°F.
• Kelvin (K) Scale:
  • Absolute zero (0 K) is the theoretical minimum temperature.
  • Water freezes at 273.15 K.
  • Water boils at 373.15 K.

Temperature Conversion

• °F = (°C × 9/5) + 32
• °C = (°F - 32) × 5/9
• K = °C + 273.15