Thermal Phys🥵🥶 Flashcards
What is thermal phys
objective and reliable way of measuring temperature
What is Temperature
Temperature is a
📍physical property of a body
📍that is related to its degree of hotness.
What is thermal Energy
Thermal Energy
📍is a form of kinetic energy
📍related to the motion of the atoms and molecules of a body.
What other form can thermal energy take that is similar to kinetic energy?
radiation from hot objects.
What is the kinetic theory of matter?
The particles in a body with a higher temperature will move
faster than the particles in a body with lower temperature.
The theory
assumes that all matter(small particles consisting of atoms or molecules) consists of particles that are in
continuous motion.
List different types of thermomemters
Laboratory thermometer
Clinical thermometer
What type of thermometer is a laboratory thermometer an illustrate it
Liquid-in-glass type of thermometer
What is thermal expansion of the mercury results
increase in the length of the liquid mercury thread in the capillary.
Length of the mercury thread ➡️ thermometric property
Why was mercury chosen for the laboratory thermometer
its temperature range (from −39 °C to 357 °C) is suitable for
laboratory use;
* it can be easily seen (it is opaque);
* its volume changes almost uniformly with temperature;
* it does not stick to glass.
The wall of the thermometer bulb is thin so that heat exchange between the bulb and surrounding can occur quickly (fast response time).
The bulb has a large volume so that the mercury thread changes by a
large amount with a small change in temperature (increased sensitivity of the thermometer-the change in its thermometric property per degree change in temperature.)
What is calibration?
Calibration is the process of
establishing the relationship between a measuring instrument and the physical quantity it is measuring.
How does calibration relate to the laboratory thermometer
calibration relates the length of the mercury thread to the temperature of the bulb as calibration requires two fixed points
Define the celcius scale
In the Celsius scale, the lower fixed point is the temperature of melting pure ice and the upper fixed point is the temperature where pure water and steam are in equilibrium.
The fixed points will be the same under given conditions (e.g. at one standard atmospheric pressure).
define a clinical thermometer
A clinical thermometer is designed to measure body temperature
when its bulb is inserted into the mouth of a person.
When the thermometer is removed from the mouth, the lower temperature outside the body causes the mercury to contract. The mercury thread breaks at the constriction allowing the observer to read the maximum temperature without worrying about the thread moving due to the environment’s lower temperature.
Advantages of thermal expansion-bimetallic strip
The bimetallic strip is made of two pieces of different metals, such as brass and steel, riveted together. When heated, brass will expand more than steel causing the bimetallic strip to bend.
The bimetallic strip is arranged so that it will bend upwards to close the electrical circuit when heated, thereby activating the electric bell.
The bimetallic strip is arranged so that it will bend downwards to open the electrical circuit when it gets too hot, thereby regulating the temperature of the oven.
Disadvantages of bimetallic strip
A 1.0 m long water pipe made of steel will expand by
1.3 × 10−5 m for every degree Celsius rise in temperature.
Imagine a 10 km long water pipe undergoing a temperature
change of 10 °C. The change in the length of the pipe would amount to 1.3 m!
Such an expansion could cause severe damages to the pipe.
