The resistance of a wire is $R$. If the length of the wire is doubled by stretching,then the new resistance will be

$A$ husband and wife have normal vision,but the fathers of both of them were colour blind. What is the probability of their first daughter being colour blind (in $\%$)?

Arrange $Ce^{+3}, La^{+3}, Pm^{+3}$ and $Yb^{+3}$ in increasing order of their ionic radii.

Which of the following does not define the functions and characteristics of plants?

$A$ current of $2\, A$ flows in a system of conductors as shown. The potential difference $(V_A - V_B)$ will be ................ $V$.

Two point charges $+8q$ and $-2q$ are located at $x = 0$ and $x = L$ respectively. The location of a point on the $x$-axis at which the net electric field due to these two point charges is zero is