Magnetic Fields (GCSE Physics)

When a coil in a magnetic field is rotated, the induced emf changes sign every half turn. Which type of current does the coil alone produce (before a commutator)?

Which material makes the best core for an electromagnet used in a transformer to increase magnetic field strength?

A student measures force on a wire: F = 0.65 N, current I = 2.0 A, length of wire in field L = 0.10 m. What is the magnetic flux density B?

Which arrangement will produce the strongest magnetic field outside a bar magnet?

Which of the following is a correct way to strengthen the magnetic field produced by an electromagnet?

What does a commutator do in a simple dynamo or DC generator?

Which property makes soft iron a suitable core for electromagnets used in transformers and relays?

Which of these will increase the voltage induced in a coil moved through a magnetic field?

Which change will increase the magnetic field strength inside a solenoid?

A teacher demonstrates induction by moving a magnet into a coil connected to an ammeter; the needle deflects while the magnet moves and returns to zero when stationary. What principle does this show?

Which statement about electromagnetic induction is correct?