4.7 Magnetism and electromagnetism

Practice questions on Magnetism and electromagnetism

• Explain why electricity is transmitted across the National Grid at high voltage and low cu… (4 marks, Explain)
• A student strokes a steel knitting needle repeatedly in the same direction with one pole o… (4 marks, Describe and Explain)
• A step-down transformer is used to reduce the potential difference from the National Grid … (4 marks, Describe)
• A student holds the north pole of a permanent magnet close to, but not touching, a steel p… (4 marks, Describe and Explain)
• Describe how magnetic field lines are used to represent the magnetic field around a bar ma… (4 marks, Describe)
• Explain how a changing magnetic field in a transformer induces a potential difference in t… (4 marks, Explain)
• Describe what happens when a piece of iron is brought close to a permanent magnet, and exp… (4 marks, Describe)
• Explain the difference between a permanent magnet and an induced magnet. (4 marks, Explain)
• Describe how an electric motor works, including how the forces on the coil cause it to rot… (4 marks, Describe)
• Explain why a current-carrying wire placed in a magnetic field experiences a force, and st… (4 marks, Explain)
• A loudspeaker contains a coil of wire placed inside a magnetic field. When a current flows… (4 marks, Explain)
• A student places a current-carrying wire between the poles of a permanent magnet. The wire… (4 marks, Explain)
• A maglev train uses the motor effect to accelerate along a track. Explain how increasing t… (4 marks, Explain)
• Explain why a transformer only works with alternating current (AC) in the primary coil and… (4 marks, Explain)
• A step-up transformer is used at a power station before electricity enters the National Gr… (4 marks, Describe)