When the speed of electrons increases, then the value of its specific charge

An oxide coated filament is useful in vacuum tubes because essentially

An electron is moving in electric field and magnetic field it will gain energy from

Answer the following questions:

$(a)$ guarks inside protons and neutrons are thought to carry fractional charges $[(+2 / 3) e ; (-1 / 3) e] .$ Why do they not show up in Millikan's oil-drop experiment?

$(b)$ What is so special about the combination $e / m ?$ Why do we not simply talk of $e$ and $m$ separately?

$(c)$ Why should gases be insulators at ordinary pressures and start conducting at very low pressures?

$(d)$ Every metal has a definite work function. Why do all photoelectrons not come out with the same energy if incident radiation is monochromatic? Why is there an energy distribution of photoelectrons?

$(e)$ The energy and momentum of an electron are related to the frequency and wavelength of the assoctated matter wave by the relations:

$E=h v, p=\frac{h}{\lambda}$

But while the value of $\lambda$ is physically significant, the value of $v$ (and therefore, the value of the phase speed $v \lambda$ ) has no physical significance. Why?

Particle nature and wave nature of electromagnetic waves and electrons can be shown by

In an electron gun, the electrons are accelerated by the potential $V$. If e is the charge and $m$ is the mass of an electron, then the maximum velocity of these electrons will be