There is a current of 8.0 A in a straight wire. The current is changed to 4.0 A in the opposite direction. Which effect does this have on the magnetic field around the wire?
It decreases in strength and acts in the opposite direction.
It decreases in strength and acts in the same direction.
It increases in strength and acts in the opposite direction.
It increases in strength and acts in the same direction.
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.