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if the electric field is directed to the right, shouldn\'t the electron charge b

ID: 1580840 • Letter: I

Question

if the electric field is directed to the right, shouldn't the electron charge be positive and not negative?

APair Of Charged Cond (Electric field (videol x (91 Electric field director - show to know when elee C Owww.chegg.com/homework-help/questions-and-answers/pair-charged-conducting -plates produces-uniform-field-1 Question: A pair of charged conducting plates produces a unif 40mm A pair of charged conducting plates produces a uniform field of 12.000 N/C directed to the right, between the plates. The separation of the plates is 40 mm. In the figure, an electron is projected from plate A, directly toward plate B, with an initial velocity of 20 x 107 m/s. The velocity of the electron as it strikes plate B is closest to: (a) 1.8 x 107 m/s (b) 1.5 × 107 m/s (c) 21 × 107 m/s (d) 2.4 × 107 m/s (e) 1.2 × 107 m/s Expert Answer Was this answer hepfu? s General guidance O Type here to search 8 4

Explanation / Answer

Ans)

Force on charge q in an electric field E is F=qE

Force on electron =-1.6x10-19Cx12000

F=-1.92x10-15

The field is positive (to the right) so the force on the electron is negative (to the left).

F=ma, so a = F/m.
Acceleration of electron a =( -1.92x10-15)/(9.1 x 10-31)

                                         = -2.10x1015 m/s2

The electron has:
initial velocity, vo = 2.0x107m/s
acceleration, a =-2.10x1015 m/s2
and has displacement s = 40mm = 0.04m
vf² = vo² +2as
= (2.0x107)² +( 2 x (-2.10x1015 ) x 0.04)
= 2.32x1014
vf =(2.32x1014)
vf= 1.5x107m/s so answer is option b