EJC Physics H217 Electromagnetic Induction - 1. Notes (2024) FULL

9749(2024) H2 Physics H217 Electromagnetic Induction – Notes Page 1 of 20 H2 Topic 17 – Electromagnetic Induction In traditional vehicles, friction is applied at the wheels to slow down the vehicle. Essentially, all of the kinetic energy of a vehicle is converted into heat each time the vehicle comes to a stop. With regenerative braking, about 60% to 70% of kinetic energy can be turned back into useful work in accelerating the vehicle subsequently. Content • Magnetic flux • Laws of electromagnetic induction Learning Objectives: Candidates should be able to: (a) define magnetic flux as the product of an area and the component of the magnetic flux density perpendicular to that area (b) recall and solve problems using Φ = BA (c) define magnetic flux linkage (d) infer from appropriate experiments on electromagnetic induction: i. that a changing magnetic flux can induce an e.m.f. ii. that the direction of the induced e.m.f. opposes the change producing it iii. the factors affecting the magnitude of the induced e.m.f. (e) recall and solve problems using Faraday’s law of electromagnetic induction and Lenz’s law (f) explain simple applications of electromagnetic induction Brake force is distributed by the on -board system between friction and regenerative braking. Some kinetic energy is transferred via the motor shaft; motor acts as a generator electronically. Kinetic energy is converted into electrical energy in the motor. Electrical energy is stored in the battery pack.

9749(2024) H2 Physics H217 Electromagnetic Induction – Notes Page 2 of 20 17.0 Introduction Earlier in electromagnetism, we learnt that (i) an electric current can produc e a magnetic field and (ii) a magnetic field can exert a force on moving charges or current -carrying conductors. As nature is often symmetric, it was later found that magnetic fields can in turn generate electric current. 17.1 E.m.f. from Motion In electromagnetism, we observe electrical energy converted into kinetic energy using an electric motor. In electromagnetism induction, we can observe, explain, and calculate the electrical energy that is converted from mechanical motion. 17.1.1 Electromagnetic Induction of straight conductor To explain why relative motion of a conductor and a magnetic field induces an e.mf., consider a thin straight conductor of length L moving at a constant speed v in a region of uniform magnetic flux density B directed normally into the plane of paper as shown. By Fleming’s left- hand rule, electrons initially experience a downward magnetic force. Negative charges accumulate at the lower end, which results in a corresponding region of positive charge at the upper end. - Inside the conductor, a potential difference is induced and results in an electric field down the length of the conductor. - Outside the conductor, it can be regarded as an induced e.m.f. that can drive current around an