Magnetic Fields (GCSE Physics)

What is the unit of magnetic flux density (B)?

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?

What is the equation linking force (F), magnetic flux density (B), current (I) and length of wire (L) in a uniform magnetic field perpendicular to the wire?

Which statement about electromagnetic induction is correct?

Why does a transformer with a 2000-turn primary and a 40-turn secondary give a lower secondary voltage than primary?

A coil of wire is moved rapidly into a region of strong magnetic field. Which of the following describes what happens?

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?

Why is a laminated iron core used in large transformers rather than a single solid block of iron?

An electromagnet’s coil is wound onto a soft iron core. If the current is switched off, why does the core lose most of its magnetism quickly?

Which factor does NOT affect the induced emf when a coil is rotated in a magnetic field?

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)?