The bright lines on an oscilloscope are due to electrons hitting the phosphorescent screen. The electrons are first accelerated by an electric field to form a horizontal beam, then deflected by a horizontal and a vertical electric field. The horizontal electric field is used to "sweep" the electron beam across the screen over a certain period of time, while the vertical electric field is controlled by the signal that is being measured.
In one oscilloscope, the electrons are initially accelerated from rest across a potential difference of V.
What is the speed u of the electron after initial acceleration? Ignore relativistic effects.
The electron has mass m
e
and charge e.
PART B
The vertical deflection field is modelled as a constant electric field of magnitude E, with a horizontal extent of d. If the electrons strike the screen at height h below the centre point of the original beam, what is the distance L to the screen from the end of the deflecting electric field?