Question

Differentiate between:

(i) Wet bulb and dry bulb,

(ii) Aneroid Barometer and Mercury Barometer.

(iii) Centigrade and the Fahrenheit.

Answer 1

(i) The dry bulb and wet bulb thermometers are two identical thermometers fixed to a wooden frame. But they are different in following way:

Dry Bulb Thermometer	Wet Bulb Thermometer
It is used to measure lowest humidity	It is used to measure highest humidity.
The bulb of the dry bulb thermometer is kept uncovered and is exposed to the air	The bulb of the wet bulb thermometer is wrapped up with a piece of wet muslin, which is kept continuously moist by dipping a strand of it into a small vessel of distilled water.
Its temperature remains high.	The evaporation from the wet bulb lowers its temperature.

(ii)

Aneroid Barometer	Mercury Barometer
Aneroid barometer gets its name from the Greek word, aneros in which ‘a’ means ‘not’, ‘neros’ means ‘moisture’, hence aneroid means without liquid. It is a compact and portable instrument.	Mercury barometer is an accurate instrument and is used as a standard. In it the atmospheric pressure of any place is balanced against the weight of a column of mercury in an inverted glass tube.
It is filled with alcohol	It is filled with mercury
It is used to measure lowest temperature.	It is used to measure highest temperature.

(iii) Both are units of measuring temperature but they have some differences.

Centigrade	Fahrenheit
On the Centigrade thermometer, the temperature of melting ice is marked 0°C and that of boiling water as 100°C, and the interval between the two is divided into 100 equal parts.	On the Fahrenheit thermometer, the freezing and boiling points of water are graduated as 32°F and 212°F respectively.
Centigrade = (Fahrenheit -32)	Fahrenheit= Centigrade \(\times \frac{9}{5} + 32\)