Question

A + 9.4 nC point charge and a - 2.31 nC point charge are 4.94 cm apart. What is the electric field strength at the midpoint between the two charges?

Answer 1

Given:

The charge is q1 = 9.4 nC

The charge q2 = -2.31 nC

The distance between them is r = 4.94 cm

To find the electric field strength at the midpoint between two charges.

Step-by-step explanation:

The electric field strength at the midpoint will be the sum of electric field strength due to q1 and q2.

The electric field strength can be calculated by the formula

`E=(kq)/(r^2)`

Here, k is the electrostatic constant whose value is

`k=9*10^9\text{ N m}^2\text{ /C}^2`

The electric field strength due to the charge q1 is

`\begin{gathered} E_1=(kq1)/(((r)/(2))^2) \\ =(9*10^9*9.4*10^(-9))/(((4.94)/(2)*10^(-2))^2) \\ =1.39*10^5\text{ V/m} \end{gathered}`

The electric field strength due to the charge q2 is

`\begin{gathered} E_2=(kq2)/(((r)/(2))^2) \\ =(9*10^9*2.31*10^(-9))/(((4.94)/(2)*10^(-2))^2) \\ =3.4*10^4\text{ V/m} \end{gathered}`

The electric field strength at the midpoint will be

`\begin{gathered} E=E_1+E_2 \\ =(1.39*10^5)+(3.4*10^4) \\ =173000\text{ V/m} \end{gathered}`

Thus, the electric field strength at the midpoint between the two charges is 173000 V/m