PhysicsUK Connections

• 4.1.1(a) Define electric current as the rate of flow of charge, I = ΔQ / Δt.
• 4.1.1(b) Define the coulomb as the unit of charge.
• 4.1.1(c) Know that the elementary charge e equals 1.6 × 10⁻¹⁹ C and that electrons and protons carry charges −e and +e respectively.
• 4.1.1(d) Understand that net charge on a particle or object is quantised and a multiple of e.
• 4.1.1(e) Understand current as the movement of electrons in metals and movement of ions in electrolytes.
• 4.1.1(f) Distinguish between conventional current and electron flow.
• 4.1.1(g) Apply Kirchhoff’s first law as the conservation of charge at a junction.
• 4.1.2(a) Define and understand mean drift velocity of charge carriers.
• 4.1.2(b) Use and apply I = A n e v, where n is the number density of charge carriers.
• 4.1.2(c) Distinguish between conductors, semiconductors and insulators in terms of number density of charge carriers.

H156 v2.0 · May 2026