An electron (charge =$1.6 \times {10^{ - 19}}C$) is accelerated through a potential of $ 100,000 V$. The energy acquired by the electron is
$1.6 \times {10^{ - 24}}\;J$
$1.6 \times {10^{ - 14}}\;erg$
$0.53 \times {10^{ - 17}}J$
$1.6 \times {10^{ - 14}}J$
An oxide coated filament is useful in vacuum tubes because essentially
An electron is accelerated through a potential difference of $200$ volts. If $e/m$ for the electron be $1.6 \times {10^{11}}$ $coulomb/kg$ , the velocity acquired by the electron will be
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?
Which of the following have highest specific charge
The ratio of momenta of an electron and an $\alpha - $particle which are accelerated from rest by a potential difference of $100 V$ is