# E Field stationary observer.

1. Apr 26, 2006

### Gott_ist_tot

I have a problem that I can not understand what I am doing wrong.

A rocket moves at 1.0*18^6 m/s. Inside is an E Field (coming out of the page of the book) that is 2.0*10^6 V/m. There is also a B Field in the rocket pointing up that is -1.0 T. What is the E Field observed by someone on Earth. (The rocket is sooming past Earth.)

I used E = E - V X B

= E - V*B (V and B are perpindicular)

= sqrt((1.0*10^6)^2 + (2.0*10^6)^2)

However this does not yield the correct answer. Any help is appreciated.
If anyone is working the numbers I got 2.24*10^6.

2. Apr 27, 2006

### marlon

a hint,

the v in the Lorentzformula that you used, does not correspond to the velocity of the rocket. This v is the velocity of the charge that moves in the E/B field. Also, the given rocket velocity is with respect to the earth, right ?

Also,

The magnitude of the E and B field are given with respect to what base exactly ? You need to know this if you wanna (which you are gonna) apply the Lorentz transformations.

What is the orbit of the rocket with respect to the earth ?

You see, there are some aspects missing in your question.

marlon

Last edited: Apr 27, 2006
3. Apr 27, 2006

### nrqed

I am surprised by tge use of a tagline to give publicity to a movie, especially for a movie treating extreme violence as entertainment. I find this disturbing on a science site.

But I realize that my opinion is not important.

Patrick