Three identical charges are placed at the vertices of an equilateral triangle. The force experienced by each charge, (if $k=1 / 4 \pi \varepsilon_0$ ) is

If $\alpha, \beta$ and $\gamma$ are the lengths of the altitudes of a $\triangle ABC$ with area $\Delta$,then $\frac{\Delta^2}{R^2}\left(\frac{1}{\alpha^2}+\frac{1}{\beta^2}+\frac{1}{\gamma^2}\right)$ is equal to

The electrons,identified by quantum numbers $n$ and $l,$ $(i)$ $n = 4, l = 1$ $(ii)$ $n = 4, l = 0$ $(iii)$ $n = 3, l = 2$ $(iv)$ $n = 3, l = 1$ can be placed in order of increasing energy,from the lowest to highest,as

$A$ simple pendulum of length $L$ is constructed from a point object of mass $m$ suspended by a massless string attached to a fixed pivot point. $A$ small peg is placed at a distance $2L/3$ directly below the fixed pivot point. The mass is displaced $5$ degrees from the vertical and released. How long does it take to return to its starting position?

What is the hybridization state of the central atom in the conjugate base of $NH_4^{+}$ ion?

An electric potential difference will be induced between the ends of the conductor shown in the diagram when the conductor moves in the direction: