PROBLEM 12.64
In Problem 12.63, determine the smallest allowable value of the
ratio de in ers Of e, m vy and if at xf, the minimum
permise distance betwen the path of the clés and the
postie plate is 0.054.
PROBLEM 12.63 Inthe choeay tube shown, clectrons emited
by the cathode and atsced by the anode passthrough a small ble
in the anode and then travel in a saigne with a speed y, until
they strike the sereon À Monsever, a diffrence of potential Yi
estolished Between the (mo parallel plates, the electrons will be
‘ubjeted 10 e force F perpendicular Lo the plates wile they travel
‘ete the pito and wil sre he soon at Poin A, which in ata
distance 3 from 4. The magntide of the fore Fis F=ea,
‘where e is the charge of an electron and dis the distance between
the plates Nepketing he ci of gig, drive an expression for
the deflection 6 in tens of Y, m, te charge and the mass m of
an election, and the dimensions, and
SOLUTION
CCamsier the mation of ne cectron Fa the horizontal motion, let = atthe el edge ofthe plate
amd X= atthe right edge ofthe plate. At the screen,
Horizon motion: There reno horizontal forces ating on te electron so that =
Let 4 =0 when the election passes the left coge of the plate, #24, when it passes the right edge, nd 1
o
i tfo
ot mitad E
ES
Vertical maton: The avi, foros acting on the el is neglestod since we ae interested in the deletion
produced by the electric farce, Whi ib electron ds wen de plates (051: 4), th vertical fee on the
lei is F, = eV. Afri passes the plates (y © #43), itis em,
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