Write name of universal and fundamental particle of matter. 

${O^{ + + }},\;{C^ + },\;H{e^{ + + }}$ and ${H^ + }$ ions are projected on the photographic plate with same velocity in a mass spectrograph. Which one will strike farthest

An electron beam is moving between two parallel plates having electric field $1.125 \times {10^{ - 6}}N/m$. A magnetic field $3 \times {10^{ - 10}}T$ is also applied so that beam of electrons do not deflect. The velocity of the electron is ............ $m/s$

A stick of $1 \,m$ is moving with velocity of $2.7 \times {10^8}m{s^{ - 1}}$. ........... $m$ is the apparent length of the stick  $(c = 3 \times {10^8}m{s^{ - 1}})$

In a Thomson set-up for the determination of e/m, electrons accelerated by $2.5$ $kV$ enter the region of crossed electric and magnetic fields of strengths $3.6 \times {10^4}V{m^{ - 1}}$ and $1.2 \times {10^{ - 3}}T$ respectively and go through undeflected. The measured value of $e/m$ of the electron is equal to

In Milikan’s experiment, an oil drop having charge $q$ gets stationary on applying a potential difference $V$ in between two plates separated by a distance $‘d’$. The weight of the drop is