Physics:Temperature

0 vs Nothing

Zero is a reference(fixed) point used when calibrating a thermometer . When an object's temperature is 0 degrees Celsius, it does have some degree of "hotness". The Celsius scale does not begin with an absolute zero degree of hotness.

"Nothing" on the other hand is different as it really means nothing at all(non existent, etc)

Using fixed scale to calibrate thermometers

Steps to calibrate the thermometer

Materials needed

Pure boiling marker

Pure melting ice

A bulb containing mercury attached to the narrow tube

A ruler and a marker

  1. Find upper fixed point (determine the length of the mercury
    column (L100) at the upper fixed point (100 °C) by placing
    the mercury tube into the beaker of pure boiling water; and
    measuring the length of the mercury column. Then make a
    marking for 100*C on the thermometer,0
  1. Find the difference of height in the mercury column between 0C and 100C and divide it by 100 to determine how far apart each 1°C marking should be
  1. Find Lower fixed point(determine the length of the mercury column (L0) at the lower fixed point (0 °C) by placing the mercury tube into the beaker of pure melting ice and measure the length of the mercury column. Then make a marking on the thermometer for 0*C

Key points to take note of

When calculating lower fixed point(ice point) a beaker of ice will be used. When it starts to melt and water is at the bottom of the beaker, there will be inaccuracies in the measurement of ice point. To prevent that, replace the beaker with a filter funnel and place the crushed ice in the filter funnel to allow the water from the melting ice to be drained away.

When calculating upper fixed point(steam point), It is better to place the thermometer above the boiling water instead of into the boiling water to measure the steam point. This is because the temperature of the boiling water is not consistent within the liquid, whereas the steam directly above the boiling water is at steam point.

Thermometric substances

Their properties

what are they

The thermometric substance is the material used in the thermometer, whose property varies with temperature

Volume of a liquid, e.g. mercury-in-glass thermometer

Electrical resistance of a wire, e.g. resistance thermometer

Electromotive force (e.m.f), e.g by a thermocouple

What is temperature?

Is a number assigned to measure a certain degree of hotness

SI unit is Kelvin(K)

Other common units are Farenheit and degrees celcius

Temperature is a scalar quantity

THey change in response to temperature change