Define least count.

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Least count is a term used in measurement that refers to the smallest unit of measurement that can be made using a particular instrument. It is defined as the reciprocal of the number of divisions on the instrument's scale.

For example, if a ruler has 10 divisions for every centimeter, its least count is 1/10 cm. The least count determines the accuracy of the measurement and is an important factor in choosing the right instrument for a particular measurement task.

Least Count

The least count is the smallest value that can be measured using a measuring instrument.

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Chapter Related Topics
Measurement of length	Unit of Velocity	Fundamental forces in nature
Measurement of mass	Unit of Acceleration	Conservation Laws in Physics
Dimensional Analysis	Unit of Force	Least Count Error

CBSE CLASS XII Related Questions

1.
Consider the nuclear reaction $ X \to Y + Z $. Let $ M_x $, $ M_y $, and $ M_z $ be the masses of the three nuclei X, Y, and Z respectively. Then which of the following relations hold true?
- $ (M_x - M_z)<M_y $
- $ (M_x - M_y)<M_z $
- $ M_x>(M_y + M_z) $
- $ M_x<(M_y + M_z) $
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2.
A charged particle $+q$ in an electric field $\vec{E}$ experiences a force in the direction of the electric field. As a result, its kinetic energy changes. Similarly, the charged particle also experiences a force when it moves in a magnetic field $\vec{B}$. But this magnetic force is perpendicular to both velocity $\vec{v}$ of the charged particle and the magnetic field $\vec{B}$, so it cannot change the kinetic energy of the charged particle. Consider two charged particles 1 and 2 of masses $m$ and $\frac{m}{2}$ having charges $-q$ and $+2q$ respectively. They are accelerated from rest through the same potential difference $V$ and acquire kinetic energy $K_1$ and $K_2$. Then they enter in a region of uniform magnetic field $\vec{B}$ perpendicular to their velocities.
3.
Consider a cylindrical conductor of length $ l $ and area of cross-section $ A $. Current $ I $ is maintained in the conductor and electrons drift with velocity $ \vec{v}_d \, (|\vec{v}_d| = \frac{eE}{m} \tau) $, where symbols have their usual meanings. Show that the conductivity of the material of the conductor is given by \[ \sigma = \frac{n e^2 \tau}{m}. \]
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Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.
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With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.
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Read the following paragraph and answer the questions that follow.
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