Electromagnetic induction
Edexcel GCSE Physics revision on Electromagnetic induction. Aligned to the Pearson Edexcel GCSE Physics 1PH0 specification. This bank has 8 practice questions on this topic.
Sample questions (3 of 8)
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Question 1
Electromagnetic induction is...
- A) Heating a coil
- B) Generating a voltage by changing the magnetic field through a conductor
- C) Pushing current with a battery
- D) Storing energy
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Answer: Generating a voltage by changing the magnetic field through a conductor
Faraday's discovery (1831): moving a magnet near a conductor INDUCES a voltage. The induced voltage drives a current if the circuit is closed. KEY: the magnetic field through the coil must be CHANGING. Either: move the magnet, move the coil, change the current in a nearby coil. This is how all electricity is generated globally (generators).
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Question 2
In a generator (dynamo), the coil rotates in a magnetic field, producing...
- A) Heat only
- B) Alternating current (AC)
- C) Direct current only
- D) Sound
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Answer: Alternating current (AC)
Coil spins. Each half-rotation, the side of the coil moves in the opposite direction through the field, so the induced current reverses. Result: ALTERNATING CURRENT. Power stations: turbines (steam from coal/nuclear/biomass; or wind, water) spin huge generators (~3000 rpm) -> AC. UK grid: 50 Hz.
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Question 3
A transformer works by...
- A) Direct contact between two wires
- B) Changing AC in one coil induces AC in another coil via shared magnetic field
- C) Compressing electrons
- D) Magnetic attraction only
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Answer: Changing AC in one coil induces AC in another coil via shared magnetic field
Transformer: primary coil + secondary coil on a shared iron core. AC in primary creates a changing magnetic field. This field induces AC in the secondary. Ratio of turns = ratio of voltages: Vp/Vs = Np/Ns. More turns in secondary = HIGHER voltage (step-up). For ideal transformer, power in = power out, so current does the opposite of voltage.
Want to test yourself on the remaining cards for this topic?
5 more questions on Electromagnetic induction — plus mistakes tracking and spaced repetition across the whole Physics spec.