Step-by-step explanation:
It is given that,
Distance between two conducting plates, d = 21 cm = 0.21 m
Electrostatic force acting on the electron placed anywhere between the two plates,
![F=3.2* 10^(-15)\ N](https://img.qammunity.org/2020/formulas/physics/college/anfja5nn8zi9csek0dzqmh6xucggc1jml6.png)
(a) Let E is the electric field at the position of the electron. The electric force acting on a charged particle per unit charge is called electric field. It is given by :
![E=(F)/(q)](https://img.qammunity.org/2020/formulas/physics/middle-school/rd627zvztvryx8r63bpbbe8cpfd3t3gkl0.png)
q is the charge on electron
![E=(3.2* 10^(-15)\ N)/(1.6* 10^(-19)\ C)](https://img.qammunity.org/2020/formulas/physics/college/h07dmlub4oi01dyhynlhkll80tpto3z53f.png)
E = 20000 N
(b) The V is the potential difference between the plates. The relation between the potential difference and the electric field is given by :
![V=E* d](https://img.qammunity.org/2020/formulas/physics/college/todcd4w3b63m3lmh8v4o5qbqvpoepzaf2m.png)
![V=20000\ N* 0.21\ m](https://img.qammunity.org/2020/formulas/physics/college/4nq1asqrgkhv7bvf3gri3raz22rkioraae.png)
V = 4200 volts
Hence, this is the required solution.