DHS 16 Electromagnetism (Notes & Tutorial)

Dunman High School (Senior High Physics) Page 1 of 18 Guiding Questions • What is a magnet? Are there “magnetic” charges? • Do magnetic fields have effects on electric charges? • What do field lines represent? Do field lines represent similar things for electric fields and magnetic fields? • Why is the word “flux” used when talking about a magnetic field? Content • Concept of a magnetic field • Magnetic fields due to currents • Force on a current-carrying conductor • Force between current-carrying conductors • Force on a charge Learning Outcomes Candidates should be able to: Magnetic Field (a) show an understanding that a magnetic field is an example of a field of force produced either by current-carrying conductors or by permanent magnets (b) sketch flux patterns due to currents in a long straight wire, a flat circular coil and a long solenoid (g) define magnetic flux density (c) use 2 oB d= µ π I , 2 Iµ= oNB r and o Iµ=Bn for the flux densities of the fields due to currents in a long straight wire, a flat circular coil and a long solenoid respectively (d) show an understanding that the magnetic field due to a solenoid may be influenced by the presence of a ferrous core Magnetic force on current- carrying conductors (e) show an understanding that a current-carrying conductor placed in a magnetic field might experience a force (f) recall and solve problems using the equation F = BIL sin θ, with directions as interpreted by Fleming’s left-hand rule (h) show an understanding of how the force on a current -carrying conductor can be used to measure the flux density of a magnetic field using a current balance (i) explain the forces between current-carrying conductors and predict the direction of the forces Magnetic force on moving charges (j) predict the direction of a force on a charge moving in a magnetic field (k) recall and solve problems using F = BQv sin θ (l) describe and analyse deflections of beams of charged particles by uniform electric and uniform magnetic fields (m) explain how electric and magnetic fields can be used in velocity selection for charged particles. 9749 H2 Physics Topic 16 : Electromagnetism Year 6 (2025) DUNMAN HIGH SCHOOL

Dunman High School (Senior High Physics) Page 2 of 18 1. Magnetic Fields due to Current (a) show an understanding that a magnetic field is an example of a field of force produced either by current-carrying conductors or by permanent magnets (b) sketch flux patterns due to currents in a long straight wire, a flat circular coil and a long solenoid 1.1 Magnetic Effect of a Current A magnetic field can be produced by: (i) Permanent magnets (ii) Current-carrying conductors The magnetic field around a permanent magnet 1 can be seen by sprinkling some iron filings around it. In 1820, Hans Christian Oersted, a Danish professor, discovered the magnetic effect of an electr