In a TV tube an electric potential difference accelerates electrons from a rest position towards a screen. Just before reaching the screen, the electrons have a wavelength of 1.2×10−11?. Determine the kinetic energy of the electrons just before they reach the screen. Your final answer should have units of eV.   Assume:  ℎ=6.63×10−34?•? ?=3.00×108?/? ??=9.11×10−31?

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In a TV tube an electric potential difference accelerates electrons from a rest position towards a screen. Just before reaching the screen, the electrons have a wavelength of 1.2×10−11?. Determine the kinetic energy of the electrons just before they reach the screen. Your final answer should have units of eV.

 

Assume: 

ℎ=6.63×10−34?•?

?=3.00×108?/?

??=9.11×10−31??

 

I attached my answer but am unsure of whether it is right.

1 = 1.2 × 10 -11m
h = 6.63 × 10 -34 j . s
m = 9.11 × 10 -3kg
v = ?
mv
h
V =
mh.
6.63×10 ~34 J.s
(9.11x10
*kg)(1.2×10 ,
'm)
= 6.06 × 10 7m/s
v = 6.06 × 10 7m/s
m = 9.11 × 10 -31kg
E = ?
E = {mv ²
-3
= }(9.11 × 10
(3.35 x 10 -15)
= 1.67 × 10 ¯15 J
'kg)(6.06 × 10 ’m/s) ²
= 1.67 ×10 ~15 ,
1.60 × 10 -19ev
= 1.05 × 10 “eV
Therefore, the kinetic energy of the electrons just before they reach the screen is 1.05 × 10 “eV.
Transcribed Image Text:1 = 1.2 × 10 -11m h = 6.63 × 10 -34 j . s m = 9.11 × 10 -3kg v = ? mv h V = mh. 6.63×10 ~34 J.s (9.11x10 *kg)(1.2×10 , 'm) = 6.06 × 10 7m/s v = 6.06 × 10 7m/s m = 9.11 × 10 -31kg E = ? E = {mv ² -3 = }(9.11 × 10 (3.35 x 10 -15) = 1.67 × 10 ¯15 J 'kg)(6.06 × 10 ’m/s) ² = 1.67 ×10 ~15 , 1.60 × 10 -19ev = 1.05 × 10 “eV Therefore, the kinetic energy of the electrons just before they reach the screen is 1.05 × 10 “eV.
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