The period of oscillation of a simple pendulum is $$T = 2\pi \sqrt {\frac{L}{g}} .$$ Measured value of $$L$$ is $$20.0 \,cm$$ known to $$1 \,mm$$ accuracy and time for $$100$$ oscillations of the pendulum is found to be $$90s$$ using a wrist watch of $$1s$$ resolution. The accuracy in the determination of $$g$$ is-
A quantity $$X$$ is given by $${\varepsilon _0}L\frac{{\Delta V}}{{\Delta t}}$$ where $${ \in _0}$$ is the permittivity of the 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-
Pressure depends on distance as, $$P = \frac{\alpha }{\beta }exp\left( { - \frac{{\alpha z}}{{k\theta }}} \right),$$ where $$\alpha ,$$ $$\beta $$ are constants, $$z$$ is distance, $$k$$ is Boltzman’s constant and $$\theta $$ is temperature. The dimension of $$\beta $$ are-