An electric motor contains a rectangular coil of wire placed in a magnetic field between two permanent magnetic poles. When a direct current (d.c.) is passed through the coil, it begins to rotate.
Explain, in terms of magnetic fields and forces, how the current in the coil causes it to spin.
State two modifications that could be made to the electrical circuit or the design of the coil to increase the rotation speed of the motor.
Describe how the direction of rotation of the motor can be reversed.
In a higher-efficiency motor design, the permanent magnets are shaped to have curved pole faces, and a cylindrical soft iron core is placed inside the rotating coil. Explain how these two design features improve the motor's performance.
7 exam-style questions on Edexcel IGCSE Physics Electromagnetism. Each one has a worked solution and a mark scheme showing where the marks go.