In Bainbridge mass spectrograph a potential difference of $1000 V$ is applied between two plates distant $1$ cm apart and magnetic field in $B = 1T$. The velocity of undeflected positive ions in m/s from the velocity selector is
${10^7}m/s$
${10^4}m/s$
${10^5}m/s$
${10^2}m/s$
An electron is moving with constant velocity along $x - $ axis. If a uniform electric field is applied along $y - $ axis, then its path in the $x - y$ plane will be
Cathode rays are similar to visible light rays in that
Write dimensional formula and electron volt of electron volt.
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?
The charge on electron was discovered by