An electric field of magnitude 1000 NC 1 is produced between two parallel plates with a separation of 2 0 - Physics -

Question

An electric field of magnitude 1000 NC−1 is
produced between two parallel plates with a separation of 2 0 cm,
as shown in the figure (a) What is the potential difference between
the plates? (b) With what minimum speed should an electron be
projected from the lower place in the direction of the field, so
that it may reach the upper plate? (c) Suppose the electron is
projected from the lower place with the speed calculated in part
(b) The direction of projection makes an angle of 60° with the
field Find the maximum height reached by the electron
Figure

Global Expert · Accepted Answer

Given:
Electric field intensity, E = 1000 N/C
Separation between the plates, l = 2 cm = 0 02 m

(a) The potential difference between the plates,
V=E l=1000×0 02=20 V
(b) The acceleration of an electron,
a=eEm⇒a=1 6×10-19×10009 1×10-31=1
75×1014 m/s2
Final velocity, v = 0

v2=u2-2al⇒0=u2-2×1 75×1014×0
02⇒ u2=0 04×1 75×1014⇒u=2
64×106 m/s

(c) Now, u = ucos60°
Final velocity, v = 0
Let the maximum height reached be s
∴v2=u2-2 as⇒s=0 497 ×10-2≈0
005 m=0 50 cm