# Electric Field Formula

Electric Field is the region produced by an electric charge around it whose influence is observed when another charge is brought in that region where the field exists.

The force F experienced by electric charge q describes the Electric field lines.

The Electric Field formula is expressed by

$E\,&space;=\,&space;\frac{F}{q}$

If q and Q are two charges separated by distance r, the Electric force is given by

$F\,&space;=\,&space;\frac{K_{q}Q}{r^{2}}$

When we substitute the electric force formula in the electric field formula, we get Electric Field Formula which is given by,

$E\,&space;=\,&space;\frac{KQ}{r^{2}}$

If the Voltage V is supplied across the given distance r, then electric field formula is given as

$E\,&space;=\,&space;\frac{V}{r}$

Electric field is measured in N/C.

Example 1

A force of 5 N is acting on the charge 6 μ C at any point. Determine the electric field intensity at that point.

Solution

Given

Force F = 5 N

Charge q = 6 μ C

Electric field formula is given by

E = F / q

= 5N / 6×10−6C

= 8.33 × 105 N/C.

Example 2

Determine the electric field at a distance of 1 A0  present from the nucleus of an Helium atom?

Solution

Given parameter is,

Charge in nucleus q = 2 x1.6 ×10-19 C

= 3.2 ×10-19 C

Distance r is 10-10 m

The formula of electric field is given as

E = Kq / r2

= 9×109 × 3.2×10−19 / (10 10)2

= 28.8 × 1010 N/c