$Ge$ and $Si$ diodes conduct at $0.3 \ V$ and $0.7 \ V$ respectively. In the following figure,if the $Ge$ and $Si$ diode connections are reversed,the value of $V_0$ changes by .....$V$.

The angle between the lines whose direction cosines satisfy the equations $l+m+n=0$ and $l^2+m^2-n^2=0$ is

From a disc of radius $R$ and mass $M$,a circular hole of diameter $R$,whose rim passes through the centre,is cut. What is the moment of inertia of the remaining part of the disc about a perpendicular axis passing through the centre?

If the line joining $A(1, 3, 4)$ and $B$ is divided by the point $P(-2, 3, 5)$ in the ratio $1: 3$,then the coordinates of $B$ are:

$A$ closed pipe is suddenly opened and changed to an open pipe of the same length. The fundamental frequency of the resulting open pipe is less than that of the $3^{rd}$ harmonic of the earlier closed pipe by $55 ~Hz$. Then,the value of the fundamental frequency of the closed pipe is: (in $~Hz$)

Which of the following bonds is the strongest?