Answer:
The speed of electron is
![8.7*10^(6)\ m/s](https://img.qammunity.org/2021/formulas/physics/high-school/8my54j66wpklc7682a6qioocffcsbfkl2b.png)
Step-by-step explanation:
Given that,
Separation of the plate = 1.20 cm
Suppose the field is
.
If the electron is accelerated from rest near the negative plate and passes through a tiny hole in the positive plate.
What the speed does it leave the hole?
We need to calculate the acceleration
Using formula of electric force
![F = qE](https://img.qammunity.org/2021/formulas/physics/high-school/mxw1w6jsl5cbzh48z0w54trx2mcsjohik0.png)
![ma=qE](https://img.qammunity.org/2021/formulas/physics/high-school/s6tlmytid2kjn6g5u1982cyxt5knmk434n.png)
![a=(qE)/(m)](https://img.qammunity.org/2021/formulas/physics/high-school/tjyd3qh342gfnnoyy6e9xwsyinjuzdttmn.png)
We need to calculate the speed of electron
Using equation of motion
![v^2=u^2+2as](https://img.qammunity.org/2021/formulas/physics/high-school/tu0wvnlno54u6y478we0vxby0r1kwunr9p.png)
![v^2=2as](https://img.qammunity.org/2021/formulas/physics/high-school/xx5agomdc3yqawk8gp9xbf1p3i9jauwt8o.png)
Put the value of acceleration in the formula
![v^2=2*(qE)/(m)* s](https://img.qammunity.org/2021/formulas/physics/high-school/cqf1wd52pu160hqpd56l735conm17jov32.png)
Put the value into the formula
![v^2=2*(1.6*10^(-19)*1.80*10^(4)*1.20*10^(-2))/(9.11*10^(-31))](https://img.qammunity.org/2021/formulas/physics/high-school/h00a6xyjmtsmerbwqjcc9o2inh7pn50h2n.png)
![v=\sqrt{2*(1.6*10^(-19)*1.80*10^(4)*1.20*10^(-2))/(9.11*10^(-31))}](https://img.qammunity.org/2021/formulas/physics/high-school/ma09aw8ydza5jyc5dxih5c8mprxyeot28m.png)
![v=8.7*10^(6)\ m/s](https://img.qammunity.org/2021/formulas/physics/high-school/ex7qrswgq3x9mp0a66l5v1akyrbdrwdgia.png)
Hence, The speed of electron is
![8.7*10^(6)\ m/s](https://img.qammunity.org/2021/formulas/physics/high-school/8my54j66wpklc7682a6qioocffcsbfkl2b.png)