The hand of a man,the wing of a bat,and the flipper of a seal represent:

Five very long,straight wires are bound together to form a small cable. Currents carried by the wires are $I_1 = 20\ A, I_2 = -6\ A, I_3 = 12\ A, I_4 = -7\ A, I_5 = 18\ A$. The magnetic induction at a distance of $10\ cm$ from the cable is

Which one of the following represents the correct order of electronegativity?

If $a = i + j + k$,$b = i + j$,$c = i$ and $(a \times b) \times c = \lambda a + \mu b$,then $\lambda + \mu = $

If $A+B=C$,then the value of $\cos^2 A + \cos^2 B + \cos^2 C - 2 \cos A \cos B \cos C$ is equal to

If $\frac{1}{2} \leq x \leq 1$,then $\cos ^{-1} x+\cos ^{-1}\left(\frac{x}{2}+\frac{1}{2} \sqrt{3-3 x^2}\right)$ is equal to