ways of measuring temperature

Question 1

explain electrical resistance when used for measuring temperatures

Answer 1

The electrical resistance of a wire increases with a
rise in temperature and the change of resistance
may be used to measure temperature. Platinum is
normally used as it has a high melting point and a
high ‘temperature coefficient of resistance”, so that
a small rise in temperature produces a (relativelylarge rise in resistance. Platinum resistance thermometers
can measure between -2()0°C and
1200ºC. Their disadvantage is that they are large
compared with thermocouples and so do not follow
rapid changes in temperature very easily

Question 2

Thermistors

Answer 2

Thermistors are semiconductor devices, which
have a negative temperature coefficient of resistance,
so an increase in temperature produces a
decrease in resistance. They are very robust and
can be made very small and so can follow rapid
changes in temperature. Their range is generally
from -70°C to 300°C, but they are less accurate
than resistance thermometers.

Question 3

Farenheit scale

Answer 3

The inventor of this scale used a freezing mixture
to give him his lower fixed point, and the boiling
point of water for the upper fixed point. The scale
was divided into 212 equal divisions, which gave
the freezing point of water as 32°F. There are 180
Fahrenheit degrees between the freezing point and
the boiling point of water (at standard atmospheric
pressure).

Question 4

two others scales of temp beside Farenhight

Answer 4

Kelvin and Centigrade