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Q. Names of units of some physical quantities are given in List-I and their dimensions formulae are given in List-Il. Match the correct pairs in the lists
List-I List-II
A $Pa-s$ (i) $\left[ L ^{2} T ^{-2} K ^{-1}\right]$
B $NmK^{− 1}$ (ii) $\left[ MLT ^{-3} K ^{-1}\right]$
C $J \,kg ^{-1} K ^{-1}$ (iii) $\left[ ML ^{-1} T ^{-1}\right]$
D $Wm ^{-1} K ^{-1}$ (iv) $\left[ ML ^{2} T ^{-2} K ^{-1}\right]$

EAMCETEAMCET 2005Physical World, Units and Measurements

Solution:

Dimensions of $Pa-s$ is
$=\left[ ML ^{-1} T ^{-2}\right] \cdot[ T ] $
$=\left[ ML ^{-1} T ^{-1}\right]$
Dimensions of $NmK ^{-1}$ is
$=\left[ MLT ^{-2}\right][ L ][ K ]^{-1}$
$=\left[ ML ^{2} T ^{-2} K ^{-1}\right]$
Dimensions of $Jkg ^{-1} K ^{-1}$
$=\left[ ML ^{2} T ^{-2}\right][ M ]^{-1}[ K ]^{-1} $
$=\left[ L ^{2} T ^{-2} K ^{-1}\right]$
Dimensions of $Wm ^{-1} K ^{-1}$
$=\left[ ML ^{2} T ^{-3}\right][ L ]^{-1}[ K ]^{-1}$
$=\left[ MLT ^{-3} K ^{-1}\right]$
So, the correct matching is (iii), (iv), (i), (ii),