Question

Suppose a diode consists of a cylindrical cathode with a radius of 6.200×10⁻² cmcm , mounted coaxially within a cylindrical anode with a radius of 0.5580 cmcm . The potential difference between the anode and cathode is 205 VV . An electron leaves the surface of the cathode with zero initial speed (vinitial=0vinitial=0). Find its speed vfinalvfinalv_final when it strikes the anode.

Answer 1

Here, the the potential difference between anode and cathode, V =205 V

So change in potential energy, ∆U =-eV , e is charge of electron

From laws of conservation of energy,

(i and f refer the initial and final state)

( change in potential energy)

( and are initial and final velocity of electron)

Initially

e = C ,m = mass of electron = Kg

m/s

So final speed of the electron when it strike the anode is m/s.