Physics Review x=6cm 5 volt Two large metal plates are separated by a 6 cm gap a
ID: 1573237 • Letter: P
Question
Physics Review x=6cm 5 volt Two large metal plates are separated by a 6 cm gap and enclosed in a vacuum tube. A 5 volt battery is connected between them as shown in the drawing What is the difference in electric potential between the plates? a) b) Define the potential energy of an electron between the plates to be zero at x = 0. What is the potential energy of the electron at x = 6 ? Give your answer twice, once in units of eV and once in units of Joules c) An electron starts at x = 0 with an initial velocity in the x-direction such that its kinetic energy is 9 × 10-19 J Which plate will the electron hit and what will its kinetic energy be when it hits? d) Repeat part c) if the electron's initial kinetic energy is 4.5 eV.Explanation / Answer
(A) Difference in electric potential between plates = 5 Volt
(B) PE = q V
= (-1.6 x 10^-19)(-5)
= 8 x 10^-19 J ........Ans
in eV = (1e)(5 volt)
= 5 eV ......Ans
(C) Applying energy conservation ,
PEi + KEi = PEf + KEf
0 + (9 x 10^-19) = (8 x 10^-19) + KE
KE = 1 x 10^-19 J Or 1eV
electron will hit the plate at z = 6 .
(D) 4.5 eV is less than 5eV so it will not be able to reach the x = 6 plates.
hence it will return to x = 0 plates.
it will hit x = 0 plate.
KE = 4.5 eV