Key Stage 5
Meaning
Electric field strength is the force per unit charge exerted on a small positive test charge placed at a point in the field.
About Electric Field Strength
- Electric field strength is given by the symbol πΈ.
- The unit of electric field strength is Newtons per Coulomb (N/C) or volts per metre (V/m).
- The direction of the electric field is the direction of the force that would act on a positive test charge.
- Electric fields can be represented by field lines; the density of these lines indicates the field strength.
Formula
Electric Field Strength is given by the general formula:
- \(πΈ=\frac{πΉ}{π}\)
Where,
πΉ is the force experienced by a charge 'Q' in the field.
and
π is the charge in that field.
The Electric field strength around a point charge is given by:
- \(πΈ=π\frac{π}{π^2}\)
Where:
π is the Coulomb's constant
π is the point charge causing the field
and
π is the distance from that point charge
Since;
- \(π=\frac{1}{4\pi\varepsilon_0}\)
Then:
- \(πΈ=\frac{1}{4\pi\varepsilon_0}\frac{π}{π^2}\)
or
- \(πΈ=\frac{π}{4\pi\varepsilon_0π^2}\)
Where:
\[\varepsilon_0\] is the permittivity of free space