Wednesday, September 7, 2022

9702_s22_qp_12 Question 2

 What is the symbol for the SI base unit of temperature? 

A

B

C °C 

D °K


ANSWER: B

The Physics Behind

  • C is the symbol used for coulomb, a unit of charge. So option A cannot be the answer.
  • °C is a unit of temperature but not its SI unit. So option C is not the answer either.
  • Temperature is a scalar quantity and in a sense must have a lowest possible value of zero unit just as other scalars like length, mass, time.... there are no negative magnitudes for these, the lowest magnitude is zero.
  • In Celsius scale, Fahrenheit scale, Rankine scale, and others, the degree symbol in corresponding units °C, °F and °R implies a "degree" or a comparison. These scales can have "negative magnitude of a scalar".
  • The SI unit of temperature is kelvin.
    • Temperature expressed in kelvins is also called the absolute temperature or thermodynamic temperature.
    • The lowest temperature in this scale is zero [absolute zero].
    • The symbol is K and not °K in relation to explanation given in bullet 4 above.



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