Electric Field

🡑 Electrostatics

All charged particles generate electric fields which cause other charged particles to experience a electrostatic force. Mathematically an electric field is represented by a vector space.

Electric field surrounding a positive charge and a negative charge respectively
Electric field surrounding a positive charge [1] and a negative charge respectively [2]

Field lines point away from positive charges and towards negative charges. The further away from the charged particles, the weaker the electric field become.

Electric field also interact with each other. Here we have electric fields with two opposite charges. Field lines point away from the positive charge and go towards the negative charge.

Image result for electric field negative point charge
Electric field with two opposite charges [3]

In the next case, there are two positive charges. All field lines point away the positive charges.

File:VFPt charges plus plus.svg
Electric field with two positive charged particles [4]

If the both charges were negative instead, the field lines would look the same but the arrows would point in the towards the charged particles.

Image result for electric field negative point charge
Electric field with two negatively charged particles [5]

Definition

If a positively charged particle was placed along a field line, it would experience an electrostatic force in the same direction as the arrow.

Conversely, if a negatively charged particle was placed along a field line, it would experience an electrostatic force in the opposite direction of the arrow.

How will charged particle q2 interact with the field lines generated by charged particle q1? [6]

Recall that Coulomb’s law determines the amount of electrostatic force and direction (attraction or repulsion) a charged particle will experience from another charged particle.

\begin{aligned} F=k_e\frac{q_1q_2}{r^2} \end{aligned}

Electric field determines the direction and electrostatic force per Coulomb of charged particle.

\begin{aligned} \vec{E}=\frac{\vec{F}}{q_2}=k_e\frac{q_1}{r^2}\hat{r} \end{aligned}

Where:

\vec{E} = the electric field generated by q_1 in newton/coulomb

\hat{r} = the unit vector from q_1 to q_2

References

[1] By User:Mfrosz – Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=1044851

[2] By E_FieldOnePointCharge.svg: User:Mfroszderivative work: Jfmelero (talk) – E_FieldOnePointCharge.svg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=5862992

[3] By Geek3 – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10508433

[4] By Geek3 – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10508472

[5] By Geek3 – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10508514

[6] Modified to label q1, q2, and r – By Geek3 – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10506218