# How to judge the character and sign of a dislocation?

I do understand that $$\mathbf b||\mathbf t$$ for screw dislocation but I am unable to judge the sign of the dislocation. Again if $$\mathbf b \perp \mathbf t$$ how do I judge its sign? Any formula which explains the sign and magnitude (to some extent) will be highly appreciated. Here, $$\mathbf{b}$$ is the Burger's vector and $$\mathbf{t}$$ is the tangent vector.

• +1 but can you tell us where you found this question? Is your $\mathbf{t}$ the "applied sheer stress" which is often denoted as $\mathbf{\tau}$? Jan 11 '21 at 6:40
• @NikeDattani Thanks.I found this question in GATE Metallurgical Engineering question papaer(which is precisely a competitive examination at the Undergrad level in India).$t$ is precisely the tangent vector.It has nothing to do with the applied shear stress. Jan 11 '21 at 7:45