If a convex lens of focal length $80 \ cm$ and a concave lens of focal length $50 \ cm$ are combined together,what will be their resulting power?

If the direction cosines of two lines are given by $l+m+n=0$ and $l^2-5m^2+n^2=0$,then the angle between them is

Two bodies $A$ and $B$ start from the same point at the same instant and move along a straight line. $A$ moves with uniform acceleration $a$ and $B$ moves with uniform velocity $V$. They meet after time $t$. The value of $t$ is:

The following series $L-C-R$ circuit,when driven by an emf source of angular frequency $70 \text{ krad/s}$,the circuit effectively behaves like:

$A$ conductor of length $1.5 \ m$ and area of cross-section $3 \times 10^{-5} \ m^2$ has an electrical resistance of $15 \ \Omega$. The current density in the conductor for an electric field of $21 \ Vm^{-1}$ is

If $n$ is an integer with $0 \leq n \leq 11$,then the minimum value of $n!(11-n)!$ is attained when a value of $n$ equals to