MCQ
In an experiment the angles are required to be measured using an instrument, $29$ divisions of the main scale exactly coincide with the $30$ divisions of the vernier scale. If the smallest division of the main scale is half- a degree $(= 0.5^o  )$, then the least count of the instrument is
  • A
    $1^o$
  • B
    $\frac{1}{2}^o$
  • $1'$
  • D
    $( \frac{1}{2})'$

Answer

Correct option: C.
$1'$
c
$30$ Divisions of vernier scale coincide with $29$
divisions of main scales
Therefore $1\,V.S.D = \frac{{29}}{{30}}MSD$
Least count  $= 1\,MSD - 1VSD = 1MSD - \frac{{29}}{{30}}MSD$
$ = \frac{1}{{30}}MSD = \frac{1}{{30}} \times {0.5^ \circ } =$ $1$ minute

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

A particle is projected vertically upwards from a point $A$ on the ground. It takes time $t_1$ to  reach a point $B$, but it still continues to move up. If it takes further $t_2$ time to reach the  ground from point $B$. Then height of point $B$ from the ground is-
Where is the value of g is maximum?
Three bodies have equal masses $m$. Body $A$ is solid cylinder of radius $R$, body $B$ is a square lamina of side $R$, and body $C$ is a solid sphere of radius $R$. Which body has the smallest moment of inertia about an axis passing through their centre of mass and perpendicular to the plane (in case of lamina)
The electrical conductivity of pure germanium can be increased by:
  1. Increasing the temperature.
  2. Doping acceptor impurities.
  3. Doping donor impurities.
  4. Irradiating ultraviolet light on it.
Two simple pendulums of lengths $1.44 \,m$ and $1\, m$ start swinging together. After how many vibrations will they again start swinging together
The specific heat capacity of a substance is temperature dependent and is given by the formula $C=k T$, where $k$ is a constant of suitable dimensions in $SI$ units, and $T$ is the absolute temperature. If the heat required to raise the temperature of $1 \ kg$ of the substance from $-73^{\circ} C$ to $27^{\circ} C$ is $n k$, the value of $n$ is. . . . . .[Given: $0 K =-273^{\circ} C$.]
An open and wide glass tube is immersed vertically in mercury in such a way that length $0.05\,\, m$ extends above mercury level. The open end of the tube is closed and the tube is raised further by $0.43 \,\,m$. The length of air column above mercury level in the tube will be ...... $m$ Take $P_{atm} = 76 \,\,cm$ of mercury 
$\overrightarrow{ A }=4 \hat{ i }+3 \hat{ j }$ and $\overrightarrow{ B }=4 \hat{ i }+2 \hat{ j }$. Find a vector parallel to $\overrightarrow{ A }$ but has magnitude five times that of $\vec{B}$.
An ideal gas has an initial pressure of $3$ pressure units and an initial volume of $4$ volume units. The table gives the final pressure and volume of the gas (in those same units) in four, processes. Which processes start and end on the same isotherm

$\begin{array}{|c|c|c|c|c|} \hline & A & B & C & D \\ \hline P & 5 & 4 & 12 & 6 \\ \hline V & 7 & 6 & 1 & 3 \\ \hline \end{array}$

In the experiment for the determination of the speed of sound in air using the resonance column method, the length of the air column that resonates in the fundamental mode, with a tuning fork is $0.1\,m$. when this length is changed to $0.35\,m,$ the same tuning fork resonates with the first overtone. Calculate the end correction  .... $m$