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9702 · 20.4

Magnetic fields due to currents

Prepare to unlock one of physics' most fascinating secrets: the connection between **electricity** and **magnetism**. You'll discover how electric currents aren't just flows of charge, but also powerful sources that generate their own **magnetic fields**. This lesson will equip you with the tools to predict these fields' directions and strengths, from simple wires to complex coils, fundamental knowledge for your Cambridge Physics exams. This pilot aligns with **Senpai Corner** A Level notes (2025–2027) for topic **20.4**.

Need to know

What you need to know

  • A current-carrying wire produces a magnetic field consisting of concentric circles.
  • The direction of the field is given by the Right-Hand Grip Rule.
  • Field strength is directly proportional to the current ($B \propto I$).
  • Field strength is inversely proportional to the perpendicular distance from the wire ($B \propto 1/r$).

Explanation

Magnetic fields due to currents

  1. A current-carrying wire produces a magnetic field consisting of concentric circles.
  2. The direction of the field is given by the Right-Hand Grip Rule.
  3. Field strength is directly proportional to the current ($B \propto I$).
  4. Field strength is inversely proportional to the perpendicular distance from the wire ($B \propto 1/r$).
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