The equivalent resistance between A and B for the mesh shown in the...

When the resistance is connected in series then the formula of equivalent resistance, $R = {R}_{1} + {R}_{2} + {R}_{3} + . . . . + {R}_{n}$, but when they are connected in parallel then net resistance is, $\dfrac{1}{R} = \dfrac{1}{{R}_{1}} + \dfrac{1}{{R}_{2}} + \dfrac{1}{{R}_{3}} + . . . + \dfrac{1}{{R}_{n}}$, so in the above diagram the equivalent resistance will be,

,

in the above branch, resistance are connected in parallel, so new equivalent resistance will be,

So, the final resistance will be, ${R}_{net} = \left(4 + 4 + 8\right)Ω = 16Ω$.