Question

The number of particles n crossing a unit area perpendicular to the x – axis in unit time can be written as $n=p\frac{(n_2-n_1)}{(x_2-x_1)}$ where $n_1$ and $n_2$ are number of particles per unit volume between length $(x_2-x_1)$. The dimensions of p are

• A. $M^{\circ }L{T}^{-1}$
• B. $M^{\circ }{L}^2{T}^{-1}$
• C. $M^{\circ }L{T}^{-2}$
• D. $M^{\circ }{L}^2{T}^4$

Answer 1

The correct option is B $M^{\circ }{L}^2{T}^{-1}$

$\left[p\right]=\frac{\left[n\right][x_2-x_1]}{[n_2-n_1]}=\frac{\left[T^{-1}{L}^{-2}\right]\left[L\right]}{\left[L^{-3}\right]}=M^{\circ }{L}^2{T}^{-1}$