For a perfectly black body,the coefficient of emission (emissivity) is:

Which one of the following oxides is expected to exhibit paramagnetic behaviour?

When a $J$-shaped conducting rod is rotating in its own plane with constant angular velocity $\omega$,about one of its ends $P$,in a uniform magnetic field $\vec B$ (directed normally into the plane of the paper),then the magnitude of the emf induced across it will be:

The energy $(E)$,angular momentum $(L)$,and universal gravitational constant $(G)$ are chosen as fundamental quantities. The dimensions of the universal gravitational constant in the dimensional formula of Planck's constant $(h)$ is

The combined equation of the diagonals of the square formed by the two pairs of straight lines given by $xy+4x-3y-12=0$ and $xy-3x+4y-12=0$ is

$A$ sinusoidal voltage of peak value $200 \ V$ is connected to a diode and a resistor $R$ in the circuit shown,such that half-wave rectification occurs. If the forward resistance of the diode is negligible compared to $R$,the rms voltage (in volt) across $R$ is approximately: