If the binding energy per nucleon in $${}_3^7Li$$ and $${}_2^4He$$ nuclei are $$5.60$$ $$MeV$$ and $$7.06$$ $$MeV$$ respectively, then in the reaction $$$p + {}_3^7Li \to 2\,{}_2^4He$$$
energy of proton must be

If the ratio of the concentration of electrons to that of holes in a semiconductor is $${7 \over 5}$$ and the ratio of currents is $${7 \over 4},$$ then what is the ratio of their drift velocities?

The time taken by a photoelectron to come out after the photon strikes is approximately

The resistance of bulb filmanet is $$100\Omega $$ at a temperature of $${100^ \circ }C.$$ If its temperature coefficient of resistance be $$0.005$$ per $$^ \circ C$$, its resistance will become $$200\,\Omega $$ at a temperature of