- Home
- Standard 11
- Physics
A student in the laboratory measures thickness of a wire using screw gauge. The readings are $1.22\,mm , 1.23\,mm , 1.19\,mm$ and $1.20\,mm$. The percentage error is $\frac{ x }{121} \%$. The value of $x$ is ..............
$100$
$150$
$98$
$140$
Solution
$X =\frac{1.22 mm +1.23 mm +1.19 mm +1.20 mm }{4}$
$X =1.21 mm$
$\Delta x =\frac{0.01+0.02+0.02+0.01}{4}=\frac{0.06}{4}=0.015$
Percentage error $=\frac{0.015}{1.21} \times 100$
$X =150$
Similar Questions
Three students $S_{1}, S_{2}$ and $S_{3}$ perform an experiment for determining the acceleration due to gravity $(g)$ using a simple pendulum. They use different lengths of pendulum and record time for different number of oscillations. The observations are as shown in the table.
| Student No. | Length of pendulum $(cm)$ | No. of oscillations $(n)$ | Total time for oscillations | Time period $(s)$ |
| $1.$ | $64.0$ | $8$ | $128.0$ | $16.0$ |
| $2.$ | $64.0$ | $4$ | $64.0$ | $16.0$ |
| $3.$ | $20.0$ | $4$ | $36.0$ | $9.0$ |
(Least count of length $=0.1 \,{m}$, least count for time $=0.1\, {s}$ )
If $E_{1}, E_{2}$ and $E_{3}$ are the percentage errors in $'g'$ for students $1,2$ and $3$ respectively, then the minimum percentage error is obtained by student no. ……. .
