What is value (magnitude) of electric field required for field emission ?
Which of the following will have the least value of $\frac{q}{m}$
Cathode rays and canal rays produced in a certain discharge tube are deflected in the same direction if
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
Which of the following is not the property of a cathode ray