Electric field
A region of space where an electric charge experiences a force. Electric field strength E is the force per unit positive charge: E = F/q, measured in N/C or V/m. Electric field is a vector quantity directed away from positive charges and toward negative charges. For a point charge Q, E = kQ/r² or E = Q/(4πε₀r²), where k = 8.99 × 10⁹ N·m²/C².
Formula
E = F/q = kQ/r²
Real World
The inkjet printer in your home uses electric fields of around 10⁶ V/m to deflect charged ink droplets onto paper with micrometre precision, forming each character.
Exam Focus
Draw field lines with arrows pointing away from positive and toward negative charges; missing arrowheads or lines touching each other loses diagram marks.
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