A current of 10A exists in a wire of cross-sectional area of 5 mm² with a drift velocity of 2 $$\times$$ 10^$$-$$3 ms^$$-$$1. The number of free electrons in each cubic meter of the wire is ___________.

The output of the given combination gates represents :

Which level of the single ionized carbon has the same energy as the ground state energy of hydrogen atom?

An electron of mass m and a photon have same energy E. The ratio of wavelength of electron to that of photon is : (c being the velocity of light)