# Beam Deflection in a Television Tube

#### daimoku

[SOLVED] Beam Deflection in a Television Tube

1. The problem statement, all variables and given/known data
Each of the electrons in the beam of a television tube has a kinetic energy of 10.8 keV. The tube is oriented so that the electrons move horizontally from geomagnetic south to geomagnetic north. The vertical component of Earth's magnetic field points down and has a magnitude of 55.0 µT.

How far will the beam deflect in moving 36.0 cm through the television tube?

2. Relevant equations

F=Bqv
F=ma
K=.5mv^2

d=vi*t + .5at^2 ???

3. The attempt at a solution

I've already completed the first two parts of the problem:
(a) In what direction will the beam deflect? East
(b) What is the acceleration of a single electron due to the magnetic field? 5.949657e14 m/s^2

I'm honestly not sure how to calculate the deflection...do I use kinematic equations? Thanks for any tips you can provide!

#### Snazzy

Figure out the time it takes to reach the end of the tube, and using this time and your acceleration that you calculated, you can find the deflection using kinematics.

#### daimoku

Doh! I knew I was overlooking something small. Had to use k=.5mv^2 for the first part to determine the velocity then plug the velocity and displacement in to find the time. Once I found the time, I used the acceleration calculated earlier and found the displacement. Simple! Thanks!

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