JEE PHYSICS MCQ: UNITS & MEASUREMENTS

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Application +4 | -1

The radius of a uniform wire is

r=0.021 \mathrm{~cm}

. The value of

\pi

is given to be 3.142. What is the area of cross-section of the wire up to appropriate significant figures?

View answer and explanation

Correct option: A

0.0014 \mathrm{~cm}^2

Option A (

0.0014 \text{ cm}^2

) is correct because the area is calculated using the formula for the area of a circle, and the result is rounded to the appropriate number of significant figures.

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\sqrt{\frac{\text { Modulus of elasticity }}{\text { Density }}}

has the unit

\mathrm{ms}^{-1} \text {. }

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\frac{1}{\left(\sqrt{\varepsilon_0 \mu_0}\right) t} \text {. }

The method of dimensional analysis can be used to derive which of the following relations? Statement-I: Dimensions of constant of proportionality of constants can be derived from dimensional method
Statement-II: Numerical value of constant of proportionality can be found from experiments only The dimensions of torque are The physical quantity having the dimensions

\left[ {{\mathrm{M}^{ - 1}}{\mathrm{L}^{ - 3}}{\mathrm{A}^2}{T^3}} \right]

is A quantity X is given by

{\varepsilon _0}L\frac{{\Delta V}}{{\Delta t}},\;

, where

{\varepsilon _0}

is the permittivity of free space, L is a length,

{\Delta V}

is a potential difference and

{\Delta t}

is a time interval. The dimensional formula for X is the same as that of