Upper fixed point is the temperature of pure water boiling at normal atmospheric pressure.Lower fixed point is the temperature of a mixture of pure ice and pure water at normal atmospheric pressure.
Each thermometer has a scale containing an upper and lower fixed points depending on the use of this thermometer for specific measurements.
The lower fixed point of a clinical thermometer is the temperature of the ice point (0°C) and the upper fixed point is the temperature of the steam point (100°C at standard atmospheric pressure). These fixed points are used to calibrate the thermometer for accurate temperature measurements.
The upper fixed point in a clinical thermometer is typically the temperature of a healthy human body (e.g., 37 degrees Celsius). The lower fixed point is usually the temperature of melting ice (e.g., 0 degrees Celsius). These fixed points help calibrate the thermometer for accurate temperature measurements.
The upper fixed point of a digital thermometer is typically set at the boiling point of water, which is 100 degrees Celsius or 212 degrees Fahrenheit. The lower fixed point is usually set at the freezing point of water, which is 0 degrees Celsius or 32 degrees Fahrenheit. These fixed points provide known reference temperatures for calibration and accuracy checks.
The lower fixed point of a thermometer is typically determined by immersing the thermometer in a mixture of ice and water. This point is known as the ice point, as it represents the temperature at which ice and water coexist in equilibrium under normal atmospheric pressure.
Mineral impurities in the upper fixed point of a mercury-in-glass thermometer can lead to an increase in the boiling point of the liquid, affecting the accuracy of high temperature measurements. Impurities in the lower fixed point can similarly impact the freezing point, affecting the accuracy of low temperature readings. Regular calibration and cleaning can help mitigate these effects.
Pure ice is used to determine a lower fixed point of a thermometer because it is a well-defined substance with a known melting point of 0°C under standard atmospheric pressure. This makes it a reliable reference point for calibrating and verifying the accuracy of a thermometer.
because the water causes the temperature to be lower
The wet bulb thermometer is typically read lower than the dry bulb thermometer because the evaporation of water on the wet bulb cools the sensor by removing heat from it. This process is known as evaporative cooling and results in a lower temperature reading on the wet bulb thermometer compared to the dry bulb thermometer.
The lower fixed point on the Celsius scale is defined as 0 degrees Celsius, which corresponds to the freezing point of water at standard atmospheric pressure. It serves as one of the reference points for the Celsius temperature scale.
The lower thermometer continued to rise dramatically after the heating ceased due to a phenomenon called thermal lag or hysteresis. This occurs because the lower thermometer takes time to adjust to the changes in temperature in its environment. Additionally, heat may still be transferring from the heated area to the lower thermometer even after the heat source is removed.
When the liquid in a thermometer gets colder, it contracts and decreases in volume. This causes it to move down the tube of the thermometer, indicating a lower temperature.
The length ,thickness, and alloy of the filament determines its resistance. The lower the resistance, the lower the voltage required to power it.