Two sources of light emit with a power of $$200 \mathrm{~W}$$. The ratio of number of photons of visible light emitted by each source having wavelengths $$300 \mathrm{~nm}$$ and $$500 \mathrm{~nm}$$ respectively, will be :

Two particles $$X$$ and $$Y$$ having equal charges are being accelerated through the same potential difference. Thereafter they enter normally in a region of uniform magnetic field and describes circular paths of radii $$R_1$$ and $$R_2$$ respectively. The mass ratio of $$X$$ and $$Y$$ is :

In the given circuit, the current flowing through the resistance $$20 \Omega$$ is $$0.3 \mathrm{~A}$$, while the ammeter reads $$0.9 \mathrm{~A}$$. The value of $$\mathrm{R}_1$$ is _________ $$\Omega$$.

In the given figure, the charge stored in $$6 \mu F$$ capacitor, when points $$A$$ and $$B$$ are joined by a connecting wire is __________ $$\mu C$$.