Subject: Science
A device, which measures the temperature of a body, is called thermometer. Three temperature scales are used on thermometers: the Celsius, the Fahrenheit, and the Kelvin scale. Most liquid thermometers use mercury or alcohol as thermometric substances. The relationship between the reading on the temperature scales is given by the relation:
Precautions while using thermometer are:
Types of thermometer according to the choice of thermometric liquid
There are two types of thermometers according to the thermometric liquid used. They are:
A mercury thermometer is used to measure the temperature of extreme hot places. Mercury thermometer can measure the temperature of -390 Celsius to 3570 Celsius.
Advantages of use of Mercury in thermometer
An alcohol thermometer is used to measure the temperature of extreme cold places. Alcohol thermometer can measure the temperature of - 1120 Celsius to 78.30 Celsius.
Advantages of use of Alcohol in thermometer
Calibration of thermometer:
Marking of temperature scale on a thermometer is called calibration. Calibration is done in two ways.
To mark the fixed points
Importance of thermometer:
Give the reason why alcohol thermometer is preferred for a very cold region.
Alcohol thermometer is preferred for a very cold region because its freezing point of alcohol is - 117°C. So, it can measure the temperature of the very cold region.
Give the reason why the temperature of boiling water can’t be measured using an alcohol thermometer.
Temperature of boiling water can’t be measured using an alcohol thermometer because the temperature of boiling water is at 100°C and that of alcohol is 78°C . So, alcohol boils before water and can’t be measured the boiling point of water.
Give the reason why constriction is made in a clinical thermometer.
Constriction presents in a clinical thermometer let the level of mercury increase when the temperature increases but doesn’t let it fall when temperature decreases and it helps to take the correct reading.
A clinical thermometer is jerked before using it.
A clinical thermometer is jerked before using it to bring the level of mercury in the bulb.
Give the reason why steel pointers are used in maximum and minimum thermometer.
Steel pointers are used in maximum and minimum thermometer to locate the temperature of the region.
Write the importance of thermometer.
Importance of thermometer are as follow:
On what principle is a thermometer based?
Thermometer is based on the principle of, ' when a body is heated it expands and when a body is cooled it contracts ’.
If you have to measure the temperature above 80°C, do you use alcohol or mercury thermometer? Why?
I use mercury thermometer to measure the temperature above 80°C because the boiling point of alcohol is 78°C . So, it can’t measure the temperature above 78°C.
What are the advantages of using alcohol instead of mercury in a thermometer?
The advantages of using alcohol instead of mercury in a thermometer are as follows:
What are the disadvantage of using alcohol instead of mercury in a thermometer.
The advantage of using alcohol instead of mercury in a thermometer is as follows:
Which thermometer do you prefer to measure the temperature of boiling water?
I prefer to use laboratory thermometer to measure the temperature of boiling water.
Which thermometer do you prefer to measure the temperature of the human body?
I prefer to use clinical thermometer to measure the temperature of human body.
The normal temperature of human body is 98.6 Fahrenheit. Convert it to Celsius.
Solution,
\begin{align*} \frac {C - 0}{100} &= \frac {F-32}{180} \\ \text {Here,}\: F =98.6\: \text {Fahrenheit} \\\frac {(C- 0)} {100} &= \frac {(98.6- 32)}{180} \\\text {or,}\:\frac {C}{100} &= \frac {66.6}{180} \\ \text {or,}\: C \times 180 &= 66.6 \times 100\: ( \text {cross multiplication}) \\ \text {or,}\: C &= \frac {666}{18} = 37^o \:\text {Celsius} \\\end{align*}
Express 0o Fahrenheit into Celsius scale.
Solution,
\begin{align*} \frac {C - 0}{100} &= \frac {F-32}{180} \\ \text {Here,}\: F = 0 \: \text {Fahrenheit} \\\frac {(C- 0)} {100} &= \frac {(0- 32)}{180} \\\text {or,}\:\frac {C}{100} &= \frac {-32}{180} \\ \text {or,}\: C \times 180 &= -32\times 100\: ( \text {cross multiplication}) \\ \text {or,}\: C &= \frac {-320}{18} = -17.7^o \:\text {Celsius} \\\end{align*}
Express 200 Fahrenheit into Kelvin.
Solution,
\begin{align*} \frac {F-32}{180} &= \frac {K-273}{180} \\ \text {Here,}\: F = 200\: \text {Fahrenheit} \\\frac {(200 - 32)} {180} &= \frac {(k- 273)}{100} \\\text {or,}\: K - 273 &= (200 - 32) \times \frac {100}{180} \\ \text {or,} \: k -273 &= (200 - 32) \times \frac {100}{180} \\ k &= 93.3 + 272 = 366.3 \\ \text {Thus,}\: 200\: \text {Farhrenheit} &= 366.6 \: \text {kelvin}\\\end{align*}
Express 100 Kelvin into Celsius.
\begin{align*} \frac {C - 0}{100} &= \frac {k-273}{100} \\ \text {Here,}\: k = 100\: \text {kelvin} \\\frac {(C- 0)} {100} &= \frac {(100 -273)}{100} \\\text {or,}\: C - 0 &= \frac {-173\times 100}{100} \\ \text {or,}\: C &= -173 \\ \therefore 100\: \text {kelvin} = -173^o \:\text {Celsius} \\\end{align*}
Convert -40 Celsius into Fahrenheit.
Solution,
\begin{align*} \frac {C - 0}{100} &= \frac {F-32}{180} \\ \text {Here,}\: C = -40\: \text {Fahrenheit} \\\frac {(-40- 0)} {100} &= \frac {(F- 32)}{180} \\\text {or,}\:\frac {-40}{100} &= \frac {F -32}{180} \\ \text {or,}\: -40 \times 180 &= (F-32)\times 100\: ( \text {cross multiplication}) \\ \text {or,}\: F - 32 &= -4 \times 18 \\ \text {or,}\: F &= -40 \\ \therefore \text {The celcius and farenheit degree coincides when the value is}\: -40 \end{align*}
Convert 200 Celsius to Kelvin.
Solution
\begin{align*} \frac {C - 0}{100} &= \frac {K-273}{100} \\ \text {Here,}\: C =200\: \text {Fahrenheit} \\\frac {(200 - 0)} {100} &= \frac {(K-273)}{100} \\\text {or,}\: K - 273 &= 200 \\ \text {or,} \: K &= 200 + 273 \\ \text {or,}\: K &= 473\: \text {kelvin} \\ \therefore 200^o \text {is equal to}\: 473\: \text {kelvin}\\\end{align*}
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