In an electron gun the potential difference between the filament and plate is $$4000 \mathrm{~V}$$. What will be the velocity of electron emitting from the gain?

An electron of mass $$m$$ and charge $$e$$ initially at rest gets accelerated by a constant field $$2 E$$. The rate of change of de-Broglie wavelength of this electron at time $$t$$ ignoring relativistic effects is

The stopping potential (V₀) versus frequency $$\nu $$ of a graph for photoelectric effect in a metal. From the graph, the Plank's constant (h) is

The de-Broglie wavelength of an electron moving with a velocity $$\frac{c}{3}$$ (c = 3 $$\times$$ 10⁸ m/s) is equal to the wavelength of photon. The ratio of the kinetic energies of electron and photon is