• Current produces a magnetic field (Oersted).
• Electromagnet coil + soft iron core; strength increases with turns, current and an iron core; temporary magnet; used in cranes and bells.
• A wire carrying current in a magnetic field experiences a force; a coil experiences torque, giving the motor.
• Motor electrical to mechanical; generator: mechanical to electrical; emf rises with rotational speed.
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Test yourself on this lesson

• The lesson’s question bank is split across the points above; each point has its own questions underneath.
• To work through the whole bank on one page: