Nearly 10% of the power of a $$110 \mathrm{~W}$$ light bulb is converted to visible radiation. The change in average intensities of visible radiation, at a distance of $$1 \mathrm{~m}$$ from the bulb to a distance of $$5 \mathrm{~m}$$ is $$a \times 10^{-2} \mathrm{~W} / \mathrm{m}^{2}$$. The value of 'a' will be _________.
A freshly prepared radioactive source of half life 2 hours 30 minutes emits radiation which is 64 times the permissible safe level. The minimum time, after which it would be possible to work safely with source, will be _________ hours.
Two lighter nuclei combine to form a comparatively heavier nucleus by the relation given below :
$${ }_{1}^{2} X+{ }_{1}^{2} X={ }_{2}^{4} Y$$
The binding energies per nucleon for $$\frac{2}{1} X$$ and $${ }_{2}^{4} Y$$ are $$1.1 \,\mathrm{MeV}$$ and $$7.6 \,\mathrm{MeV}$$ respectively. The energy released in this process is _______________ $$\mathrm{MeV}$$.
The stopping potential for photoelectrons emitted from a surface illuminated by light of wavelength 6630 $$\mathop A\limits^o $$ is 0.42 V. If the threshold frequency is x $$\times$$ 1013 /s, where x is _________ (nearest integer).
(Given, speed light = 3 $$\times$$ 108 m/s, Planck's constant = 6.63 $$\times$$ 10$$-$$34 Js)