Sodium and copper have work functions $$2.3$$ $$eV$$ and $$4.5$$ $$eV$$ respectively. Then the ratio of the wavelengths is nearest to

Formation of covalent bonds in compounds exhibits

By increasing the temperature, the specific resistance of a conductor and a semiconductor

Capacitance (in $$F$$) of a spherical conductor with radius $$1$$ $$m$$ is