Which of the following modifications will not increase the magnetic field strength inside a current-carrying solenoid?
Replacing the soft iron core with a plastic core
Increasing the current in the solenoid
Increasing the number of turns per unit length of the solenoid
Connecting the solenoid to a power supply with a higher voltage
17 exam-style questions on OCR GCSE Physics Magnets and magnetic fields. Each one has a worked solution and a mark scheme showing where the marks go.