In a television tube, electrons travel down the tube and strike the fluorescent material at
the end of the tube. Their impact with this material causes light to be emitted, thereby producing
the picture we see. The electrons are accelerated from rest to a speed of 2 x 108 ms-1 in a distance
of 1.50 cm.
(i) What is the acceleration of an electron during this process? (10 marks)
(ii) How long does the acceleration take?
(i) the acceleration I calculated seems WAY too large. I know the acceleration will be big, but I didn't think it could exceed the speed of light due to the theory of relativity.
(ii) the time to accelerate makes sense, but I think its wrong because I calculated the acceleration wrong.
The Attempt at a Solution
(i) I used the equation that doesn't involve time, only velocity, initial velocity, position and time:
v^2 = v^2(0) + 2a (x - x0)
(2*10^8)^2 = 0 + 2a (0.015m - 0)
a = 1.3 * 10^18 ???
(ii) with a = 1.3 * 10^18, I just plugged it into x = 0.5a(t^2), solved for t and got t = 1.5 * 10^-10 s