PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
In a cathode-ray tube, a narrow electron beam passes between two parallel metallic plates that are 2.5cm long and 4.0mm apart. The plates are maintained at a potential difference of 400V.
(i) Compute the magnitude of the electric field in the region between the plates.
(ii) Determine the work done by this field in moving a single electron from the negatively charged plate to the positively charged plate.
(iii) If the separation between the plates is increased to 6.0mm but the electron beam is required to experience the same electric field as in part (i), what potential difference should now be applied across the plates?