- #1

dmitriylm

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## Homework Statement

Have a few questions on CRT's. If we are given the accelerating voltage (250V) how would I calculate the kinetic energy of the electron as it leaves the positive end of the charge area? What is the formula for the speed of an electron along the tube (vz) as it leaves the positive charge area, in terms of the accelerating potential Va and the mass and charge of an electron.

## Homework Equations

F = qE=ma

KE= (1/2) mv^2

## The Attempt at a Solution

Having only been given the accelerating voltage (250V) I'm not sure where to begin. We did all kinds of stuff with kinetic energy in Newtonian physics but I'm not sure how to apply it with voltage.

I think at some point I arrived at

qV=(1/2)mv^2

(-1.6x10^-19)(250) = (1/2)(9.11x10^-31)v^2

v = +/- 9.371x10^6 i

KE = (1/2)(9.11x10^-31)(9.37x10^6) = 4.268035x10^-24

If a=qE/m and we know the q charge value for an electron, we know the mass of an electron, how do I find the E value produced by 250V?

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