Q. Suppose $u_{1}$ and $u_{2}$ are the units selected of a physical quantity in two systems of measurement and $n_{1}$ and $n_{2}$ are their numerical values, then which of the following is correct ?

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A

$n_{1}u_{1}=n_{2}u_{2}$

B

$n_{1}u_{1}+n_{2}u_{2}=0$

C

$n_{1}n_{2}=u_{1}u_{2}$

D

$\left(\right.n_{1}+u_{1}\left.\right)=\left(\right.n_{2}+u_{2}\left.\right)$

Solution:

Physical quantity $\left(\right.p\left.\right)=Numericalvalue\left(\right.n\left.\right)\times Unit\left(\right.u\left.\right)$
If physical quantity remains constant then $\text{n} ∝ \frac{1}{\text{u}}$
$∴ \, \, \, \text{n}_{1} \text{u}_{1} = \text{n}_{2} \text{u}_{2}$

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