Question

You have a horizontal cathode ray tube (CRT) for which the controls have been adjusted such that the electron beam should make a single spot of light exactly in the center of the screen. You observe however that the spot is deflected to the right. It is possible that the CRT is broken. But as a clever scientist you realize that your laboratory might be in teh middle of a electric or magnetic field. Assuming that you do not have a compass, anymagnets, or any charged rods, how do you use the CRT itself to determine if the CRT is broken, in an electric field, or in a magnetic field?You cannot remove the CRT from the room>

Answer 1

Answer:

Explanation:

Rotate it slowly to establish whether the spot moves. If it is broken, it will stay as it is. By rotating it the electrons' path to the centre of the screen will be tilted to another position by any external disturbing field.