A student investigates the factors affecting the turning effect (torque) on a current-carrying coil situated in a magnetic field. The student can change the strength of the magnetic field and the cross-sectional area of the coil. Which two changes together must decrease the turning effect?
decreasing the magnetic field strength and decreasing the area of the coil
decreasing the magnetic field strength and increasing the area of the coil
increasing the magnetic field strength and decreasing the area of the coil
increasing the magnetic field strength and increasing the area of the coil
275 exam-style questions on CIE IGCSE Physics 4.5 Electromagnetic effects, covering 4.5.1a Electromagnetic induction, 4.5.1b Direction of an induced e.m.f., 4.5.2 The a.c. generator, 4.5.3a Magnetic effect of a current and its applications, 4.5.3b Strength and direction of the field around wires and solenoids, 4.5.4a Force on a current-carrying conductor, 4.5.4b Force on beams of charged particles, 4.5.5 The d.c. motor, 4.5.6a Construction and operation of a transformer, 4.5.6b Turns ratio and current in a transformer, and 4.5.6c High-voltage transmission of electricity. Each one has a worked solution and a mark scheme showing where the marks go.