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  $(c = 3 \times {10^8}m{s^{ - 1}})$

An electron gun with its collector at a potential of $100\; V$ fires out electrons in a spherical bulb containing hydrogen gas at low pressure $(\sim 10^{-2} \;mm$ of $Hg$ . A magnetic field of $2.83 \times 10^{-4}\; T$ curves the path of the electrons in a circular orbit of radius $12.0 \;cm .$ (The path can be viewed because the gas tons in the path focus the beam by attracting electrons, and emitting light by electron capture; this method is known as the 'fine beam tube' method.) Determine $e / m$ from the data.

When cathode rays (tube voltage $~ 10 kV$) collide with the anode of high atomic weight then we get

Which is not true with respect to the cathode rays

Explain emission of electron from metal. Define work function. Write its unit, work function of metal depend on which factors ? 

Cathode rays enter into a uniform magnetic field perpendicular to the direction of the field. In the magnetic field their path will be