PhysicsUK Connections

Connections.EXPLORE · CONNECT · UNDERSTAND YOUR COURSEOCR A · AS Physics Browse topics →
All apps ↗
55 ideas · 69 connections
Charge flow and electrical power Current connects microscopic drift with charge transfer Kirchhoff’s first law conserves charge Kirchhoff’s second law tracks energy per charge Build a resistor network from Ohm’s law A potential divider uses shared current Changing resistance makes a voltage sensor Read circuit connections, not the drawing’s shape Charge and current4.1 Energy, power and resistance4.2 Charge4.1.1 Mean drift velocity4.1.2 Circuit symbols4.2.1 E.m.f. and potential difference4.2.2 Resistance4.2.3 Series and parallel circuits4.3.1 Potential dividers4.3.3
100%

Select a node to explore. Select a green line to follow a connection.

Drag to pan · scroll to zoom · arrow keys to move · 0 to fit

Physics connection Topic → subtopic
Explore the connections 69
PHYSICSUK CONNECTIONS
Physics connection

Kirchhoff’s first law conserves charge

OCR A AS Physics · Two ideas, one explanation

Charge does not steadily accumulate at a junction in a steady circuit. The rates of charge entering and leaving must therefore balance.

ΣIin = ΣIout

Follow the reasoning

  1. Mark current directions at the junction.
  2. Add currents entering and leaving separately.
  3. Use the balance to find the unknown branch current.
Specification outcomes (4)
  • 4.1.1(a) Define electric current as the rate of flow of charge, I = ΔQ / Δt.
  • 4.1.1(g) Apply Kirchhoff’s first law as the conservation of charge at a junction.
  • 4.3.1(b) Apply Kirchhoff’s first and second laws to analyse electrical circuits.
  • 4.3.1(e) Analyse circuits with components including both series and parallel arrangements.
Open the official OCR AS specification ↗

H156 v2.0 · May 2026

OFFICIAL EXAM-BOARD RESOURCES

See it in an exam

A curated collection of checked examples. Coverage is growing; this is not a complete past-paper catalogue.

ORIGINAL PHYSICSUK QUESTIONS

Put the ideas to work

More practice is on its way

No PhysicsUK question linked yet. New eligible questions appear here as the bank grows.

PhysicsUK · Built for understanding