Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.
Understanding
- I can write the Biot-Savart law, dB = (μ₀/4π) I dℓ × r̂ / r², and explain each symbol. (Guide: “The Biot-Savart law”)
- I can describe the field around a wire as circles centred on it, with no component toward, away from or along the wire. (Guide: “Direction: the right-hand grip rule”; Practice Q1)
- I can explain why a piece of wire aimed straight at a point adds no field there. (Guide: “Loops and arcs”)
- I can explain why only the axial components survive on the axis of a loop. (Guide: “The field on the axis of a loop”; Practice Q6)
Calculation and skills
- I can derive the field on the perpendicular bisector of a finite straight wire and show its long-wire limit. (Guide: “Finite straight wire”; Worked example 1; Practice Q4)
- I can derive and use μ₀I/(2R) for a loop and μ₀Iφ/(4πR) for an arc. (Guide: “Loops and arcs”; Practice Q2)
- I can use the on-axis field of a loop or flat coil, and its 1/z³ far-field form. (Guide: Figure 2; Practice Q5)
- I can add fields from wires and loops, taking care with directions. (Guide: Worked example 2; Practice Q6)
- I can calculate F = IℓB sin θ for a straight wire in a uniform field. (Practice Q3)
- I can integrate dF = I dℓ × B for a curved wire or a non-uniform field. (Guide: Worked example 3; Practice Q7)
Reasoning
- I can predict whether two parallel currents attract or repel, and find the force per length. (Guide: “Force on a current-carrying wire”)
- I can predict a factor of change in B, such as the effect of changing I and R together. (Practice Q2)
- I can sketch how B varies with distance from a wire or along a loop’s axis. (Guide: Figure 2; Practice Q6)
All ticked? Move on to Ampère’s law (Topic 12.4), or return to the course roadmap.