- Home
- Standard 11
- Physics
1.Units, Dimensions and Measurement
medium
The following observations were taken for determining surface tension $T$ of water by capillary method:
diameter of capillary, $D= 1.25 \times 10^{-2}\; m$
rise of water, $h=1.45 \times 10^{-2}\; m $
Using $g= 9.80 \;m/s^2$ and the simplified relation $T = \frac{{rhg}}{2}\times 10^3 N/m$ , the possible error in surface tension is ........... $\%$
A
$0.15 $
B
$1.5$
C
$2.4$
D
$10$
(JEE MAIN-2017)
Solution
$\mathrm{T}=\frac{\mathrm{rhg}}{2} \times 10^{3} \mathrm{N} / \mathrm{m}$
$\frac{\Delta \mathrm{T}}{\mathrm{T}}=\left|\frac{\Delta \mathrm{r}}{\mathrm{r}}\right|+\left|\frac{\Delta \mathrm{h}}{\mathrm{h}}\right|=\frac{0.01}{1.25}+\frac{0.01}{1.45}$
$\%$ error $=\frac{\Delta \mathrm{T}}{\mathrm{T}} \times 100=\frac{1}{1.25}+\frac{1}{1.45}=0.8+0.69=1.5 \%$
Standard 11
Physics
