Question

Draw the force that Q feels as a bold arrow pointing from the charge. Q= 5 coulombs x = 2 meters V=100 volts across the plates. For the parallel plate arrangement, the voltage and electric field are related by the spacing between the plates like this : V= Ex. How much energy is that in Joules? Remember that energies expressed in electron volts are: 1 eV= 1.6 x 10^-19 J. What is the energy of each electron in electron volts?

Answer 1

The charge is given as,

`Q=5\text{ C}`

The potential difference is given as,

`V=100\text{ V}`

The potential difference is defined as the work done per unit charge. Mathematically,

`V=(W)/(Q)`

Here, W is the work done that is stored in the form of energy. Therefore,

`W=VQ`

Substituting all known values,

`\begin{gathered} W=(100\text{ V})*(5\text{ C}) \\ =500\text{ J} \end{gathered}`

Therefore, the energy is 500 J.

The energy of each electron placed between the charged plates is given as,

`W=qV`

Here, q is the charge on the electron.

Substituting all known values,

`\begin{gathered} W=(1.6*10^(-19)\text{C})*(100\text{ V}) \\ =1.6*10^(-17)\text{ J} \end{gathered}`

Since we know that 1 eV equals 1.6*10^(-19) J.

Therefore, the energy of each electron in eV is given as,

`\begin{gathered} W=(1.6*10^(-17)\text{ J})*(\frac{1\text{ eV}}{1.6*10^(-19)\text{ J}}) \\ =100\text{ eV} \end{gathered}`

Therefore, the energy of each electron is 100 eV.