Page 305 - General Knowledge

GENERAL KNOWLEDGE 2019

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 Centigrade Scale: In this scale, ice point and steam point are taken as 0 C and 100 C. 1 C
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is equal to 100 part of difference between two points.
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 Fahrenheit scale: In this scale, ice point and steam point are taken as 32 F and 212 F. 1 F is
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equal to the 180 part of difference between two points.
 Kelvin scale: In this scale, ice point and steam point are taken as 273 K and 373 K. 1 K is
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equal to the 100 part of difference between two points.
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 Rankine scale: In this scale, ice point and steam point are taken as 460 Ra and 672 Ra.
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1 Ra is equal to the 212 part of difference between two points.
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 Reaumur scale: In this scale, ice point and steam point are taken as 0 R and 80 R. 1 R is
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equal to the 80 part of difference between two points.
Thermometer
 A thermometer is an instrument for measuring temperature.
 To calibrate a thermometer two temperature called fixed points are chosen and the interval
in between them is divided into a number of equal spaces called degrees.
 In this way we obtain a temperature scale.
 The lower fixed point called the ice point is the temperature of pure melting ice a standard
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pressure i.e. 0 C
 The upper fixed point called the melting point is the temperature of steam from pure boiling
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water at standard pressure i.e. 100 C.
 On the Celsius or Centigrade scale
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 Lower point = 0 C , Upper point = 100 C
 The interval divided into 100 degrees.
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 We may also use the Kelvin scale where, Kelvin = degree Celsius + 273K = C + 273
 We know that to convert any temperature in degrees Celsius to Kelvin we must add 273.
 In many applications, it is a change in temperature that is more important than the actual
initial and final temperatures.
 Where the change in temperature is delta T and each temperature T 1 and T 0 are given in
degrees Celsius. Therefore

 In degrees Celsius,
( ) ( ) ( )

 In Kelvin,
( ) ( ) ( ) ( ( ) ) ( ( ) )

 Since the 273 values cancel each other out
( ) ( ) ( ) ( )

 So for changes in temperature the value of the change in temperature in degrees Celsius is
the same as the value of the change in temperature in Kelvin.
Change in Temperature
 The change in temperature which a material experience depends on three factors.
 The type of material
 The mass of the material
 The amount of heat energy given to the material.

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