THOMSON TUBE

Thompson Tube is used to study the effect of electric and magnetic field on electron. A high voltage is applied between anode and cathode. Electrons are therefore emitted from cathode and accelerated towards anode. Cathode is maintained at ground potential. So electrons are emitted from cathode with a kinetic energy proportional to the anode voltage. These emitted electrons from cathode are then accelerated towards anode and pass horizontally through a slit behind the anode. These energetic electrons then impinge upon fluorescent where they are observed. A plate capacitor is used to displace the electrons vertically upward or downward in fluorescent screen. Helmholtz's coils are used to produce a horizontal magnetic field which moves the electrons in the vertical directions