What will increase the strength of the magnetic field around a current?
Increasing the current
Moving further from the current
Switching the current off
What is the effect of putting an iron core inside a solenoid?
The magnetic field gets weaker
The iron core cancels the magnetic field
The electromagnet becomes stronger
An electric current flows through a wire. What happens to the magnetic field strength when the wire is shaped into a solenoid?
It increases
It stays the same
It decreases
What do a bar magnet and a solenoid have in common?
They are both permanent magnets
Their magnetic fields have a similar shape
They are both types of electromagnet
Which of the following does not increase the strength of the magnetic field produced by an electromagnet?
Increasing the electric current flowing in the coil
Increasing the number of turns on the coil
Using a copper core
When using Fleming's left hand rule, what does the thumb represent? - Higher
Current
Force
Magnetic field
0.4 A flows in 0.1 m of wire in a 0.7 T magnetic field. What force acts on the wire?
0.21 N
2.8 N
0.028 N
In a dc motor, what is the function of the split ring commutator?
It reverses the current direction every half turn, to keep the motor spinning in the same direction all the time
It shields the magnetic field from acting outside the motor case
It strengthens the magnetic field to make the motor spin fast on a lower current
How do headphones generate sounds?
They contain small loudspeakers
The headphone wires carry sound waves to the ears
The sounds are generated by the electronic music device, rather than the headphones themselves
What are the main components in a loudspeaker?
Coil of wire, split ring commutator, cone
Coil of wire, permanent magnet, cone
Permanent magnet, split ring commutator, cone