Physics

Problem

In a cathode-ray tube, a narrow electron beam passes between two parallel metallic plates that are

2.5\,\text{cm}

long and

4.0\,\text{mm}

apart. The plates are maintained at a potential difference of

400\,\text{V}

. a. (i) Compute the magnitude of the electric field in the region between the plates. b. (ii) Determine the work done by this field in moving a single electron from the negatively charged plate to the positively charged plate. c. (iii) If the separation between the plates is increased to

6.0\,\text{mm}

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?

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