$750=\frac{\mathrm{P}}{2} \sqrt{\frac{\mathrm{T}}{\mu}} \ldots . .(1)$
$1000=\frac{\mathrm{P}+1}{2} \sqrt{\frac{\mathrm{T}}{\mu}} \ldots . .(2)$
$\frac{4}{3}=\frac{\mathrm{P}+1}{\mathrm{P}} \quad \therefore \mathrm{P}=3$
$\Rightarrow 1000=\frac{4}{2} \sqrt{\frac{\mathrm{T}}{2 \times 10^{-5}}} \therefore \mathrm{T}=5 \mathrm{~N}$
