# Deflection of an electron due to gravity.

1. Jan 16, 2008

### theinfojunkie

1. The problem statement, all variables and given/known data
There are two parts to the question.
A)Why is gravity not important during JJ Thomsons experiment?
b)what is the deflection due to gravity?
Given variables.
In a thomson spectromoter set at 10^4 (V/m). deflection with out the magnetic field applied equals .10 radians over a L of .050 m.
Speed of electron with magnetic field applied is 2.9x10^7 m/s.
Strength of Magnetic field is 3.4x10^-4 T.

2. Relevant equations
I don't know what they are....

3. The attempt at a solution
A) in the experiment the effects of gravity were negated by the application of a magnetic field perpendicular to that of the electric field, to help over come any deflection caused by gravity.
B) I really don't know how to go about this.
EDIT:
I thought about it a little more...would I just be using the velocity, time distance and deflection angle to solve this??
Like...a particle fired at a zero degree angle?

Last edited: Jan 16, 2008
2. Jan 17, 2008

### theinfojunkie

Alright so as far as I have it figured.
v(y) = gt

then take v(y)/v(x) and take the inverse tan of it to get the answer.
It gives the angle of deflection in radians. The answer I got does not match that of the book but is close enough. It's a very small number.
the answer the book was looking for was 10^-15 m.

Now if it's done by taking .5(at^2) i get another answer, but the order is wrong. It comes out to something like 1.7x10^-17 or something or other.

Any ideas what exactly they did??

3. Jan 17, 2008

### Marco_84

is it a GR problem or wat do you need to use GR Action or What???

4. Jan 18, 2008

### theinfojunkie

General Relatvity??
No it is not. The speed is to slow.